Assigning Retainers

[MistakeNot]

As a final piece of advice: Only make a retainer a FSH if you already have all the other options (battle class/MIN/BOT). Fisher is easily the least useful of the retainers - there are many fishes it can't bring back, and of the ones it can catch only a handful are useful.

If you only have two retainers (which is the default unless you pay extra for more) then make one of them your main class and the other either a Miner or a Botanist OR make them Miner and Botanist. (Assuming you yourself level up MIN/BOT of course.)
Both variants are good and useful, and it is pretty much a matter of taste which to use.

Retainers with a battle class/job (such as WHM) can indeed bring back hides/skins and bones and other animal parts that can be obtained as drops from enemies. Nearly all of these are used in crafting - in particular Leatherworkers need all those hides to make leather, Culinarians need meat and eggs for many recipes, and so on.

You can of course buy all crafting materials from the Marketboard, but it can get very expensive to do it that way.

Retainers provide a way of getting crafting materials while you do something else, instead of you going out there and gathering it all yourself.