I do like PM's as a conservative piece of my overall financial situation. Sort of like insurance or an alternative savings plan. I like them for protection against high inflation, currency debasement and even an outright economic collapse. They generally move opposite to more modern instruments like stocks and such which is nice. For most people assuming they are halfway financially squared away (no huge credit card balances, etc) putting some money into PM's makes sense.
Brick and mortar dealers are often coin shops that deal numismatic stuff and have bullion as a sort of side effort. Also pawn shops and some jewelry stores deal in bullion. Brick and mortar stores have some advantages. The first advantage is that they are convenient. Hard to beat picking up a silver round or a small gold coin every payday on the way home. Also if you decide to pay cash they have the factor of discretion. Personally I just can't see Cops kicking in the doors of everybody who bought a few silver rounds or a gold coin so this is not much of a concern for me. Another advantage is that some of these folks can help you learn about PM's. The old guy hanging out in his coin shop might be willing to help you learn about different types of coins and maybe eventesting silver and gold or grading coins. Also if it is a small shop and you are a good customer they may give you a call when products you like come in. Furthermore the coin/ pawn shop guy can be a good "grey world" contact who knows how to get stuff.
This is not to say that brick and mortar shops don't have disadvantages. The biggest disadvantage of brick and mortar dealers is often price. Some of them for whatever reason charge crazy prices. I once laughed in a coin shop guys face when he wanted $10 OVER SPOT for beaten up no name 1 ounce silver rounds. It varies shop to shop based on their business model, competition and how informed their customers seem to be. Heck it may even change based on how much they think they can get away with on a given customer. The next disadvantage is often availability. Especially with the folks who have bullion as a side business like numismatic coin or collectibles dealers and pawn shops they predominantly sell what they have bought. This means they may have 90% silver one week, 1 ounce rounds the next, a couple 1/4 ounce Eagles here and some Krudgerrands there. Since brick and mortar stores are a local thing I can't make any meaningful recommendations but I have had good dealings with a few in the past.
Online dealers like JM Bullion tend to have the best prices and greatest availability which are their biggest advantages. Also comparison shopping is easy and you can do it on a Sunday morning in a bathrobe. The first downside is that you have to pay shipping. One absolutely must consider this in their "is this a good deal" calculation. It also makes frequent small purchases cost prohibitive. Paying $5 or 8 to ship something worth $35 or $40 is cost prohibitive for sure. That it is difficult to impossible to be anonymous could be a disadvantage or turn off for some folks. Also if for whatever reason you needed to turn cash into metals TODAY an online dealer would not be a wise route.
One of the biggest benefits of established dealers who make their living selling metals is that their livelihood rests on their reputation. If through bad intentions or neglect they sell some fake stuff they are totally hosed. Due to this they are as a rule honest and above board in their dealings. This doesn't mean they they will always have competitive prices just that the products will be what they are sold as.
Personal transactions vary from boringly easy to the wide open wild west. I have purchased silver from a family member. I had some cash and they had some silver and we swapped. Online type purchases of PM's from private folks have, at least IMO an uncomfortably high likelihood of fraud. I have been burned in a small way on Ebay and will not make that mistake again. Also there is just so much fake gold floating around. In the last few years some really legit looking stuff has came out of China.
Silver can be purchased in two basic products, pre '64 90% silver and 99% bullion. There are other options but we are keeping it simple here.Pre '64 90% silver is dimes, quarters, 50 cent pieces and silver dollars made before 1964. Yes our change was made of silver. The stuff I am talking about has no real numismatic (collector) value and typically dates from the early 1900's to 1964. The advantage of this stuff is that it is in small pieces. A dollars worth of silver is right about .77 of a troy ounce of silver. Thus a dime is about .07, etc. I am too lazy to look up and type all the exact weights but you can look them up here. The other option is 99% silver bullion. This is rounds or bars or ingotts made of as close to pure silver as one can easily get. Some like Eagles or Canadian Maple Leafs are minted by a country and many others are made by numerous private mints.These are made in all sorts of weights but 1, 5, 10 and 100 ounce are the most common.
Both have advantages and disadvantages. 90% silver is in small denominations. At today's prices even one ounce rounds are too large to make small transactions like a few groceries. Also they are readily recognizable at least to folks who know our change used to be made of silver. The biggest disadvantage is that many dealers charge almost crazy premiums if you buy this stuff in small (under $100 face value which is 70 some odd ounces and costs about $2,300 bucks) amounts. Montana Rarities treats small 90% silver customers well.
Bullion is generally a bit cheaper per ounce [Remember for these purposes you are buying METAL, not a coin or whatever. Thus the goal is to get as much METAL as possible for your dollars.] than 90% silver. Also it is typically in convenient weights. If the going trade is an ounce of silver for 5 pounds of beef or 20 pounds of wheat (or whatever) it is a lot easier to have nice round denominations. Also some folks say that it is good for a coin/ ingot to say it's content and purity ie "One ounce of .999 pure silver". These folks thing people who are less than knowledgeable about PM's may be more inclined to accept their value.
Whatever you decide to go with silver is a great place to start. First of all it is reasonably affordable. Second of all it is in small enough denominations to sell a coint or two to a dealer and buy groceries or a tank of gas or to barter a little bit at a time to get whatever. I would recommend purchasing a pretty good amount of silver before thinking about gold. If you are into round numbers maybe $100 face (70 some odd ounces) or 100 ounces of bullion could work but it all varies based on your situation.
Silvers biggest advantage is that it's affordable. The biggest disadvantage of silver is that at some point it gets HEAVY. I know a guy who needs to use a truck to move his silver, while that is a nice problem to have he would face some hard choices if he needed to evacuate in a hurry. This brings us to gold.
Gold is a lot more expensive than silver and could be a bit overpriced right now, at least in relation to silver which is probably a better deal at this time. It is sitting somewhere around $1,560 an ounce. Gold comes in two basic varieties. Old coins and bullion. Old coins are just that, old coins from back when Gold was money. Bullion and new coins such as Eagles, Maple Leafs and Krudgerrand's pretty much fall into the same group. Sometimes you can get good deals on the old coins, particularly European coins from aprox 1890-1917. Just be sure to stick to ones folks will recognize like Swiss and French Francs, British Sovereigns and the like. New coins/ bars are convenient because they are typically in nice round (1/10th, 1/4, 1/2 and 1 ounce) sizes and have the weight and purity clearly written on the coin. I don't find one vastly superior to the other. Even weights are nice but old coins are kind of cool too. One notable advantage of old coins (not numismatic/ collectable, just old very common coins in ok condition) is that they are typically the lowest premium way to buy small gold.
As we said before buy small gold before large gold. Small gold would be gold coins that are part of an ounce, typically 1/10th and 1/4 ounce and are also called fractional coins. As to how much of this stuff to buy before going to large gold (one ounce coins/ bars) I would say at least a couple ounces, maybe a few. For large gold I would purchase one ounce coins or ingots. I don't see a reason to get anything bigger than that. For large gold I would just be sure to get something common like Eagles, Maple Leafs, Krudgerrands or Credit Swiss ingots.
As we talked about Golds biggest advantage (already considering that it is durable, recognizable, divisible and there is consistent demand for it) is that it is a very compact store of value. For the price of a one ounce gold coin you could get a nice bag of silver or a lot of other stuff. One could toss 50k in gold into a daypack and evacuate or into a ruck to GOOD but silver would be problematically heavy. Also gold has a certain allure and enough folks have been able to use it to bribe/ buy their way out of a warzone or terrible situation that it bears considerations.