So I just finished Fire Emblem: Awakening and I started playing without ANY knowledge of the game and I can't help but think that if I had a basic grasp on the game play/marriages/spot pass my game would have been SO MUCH BETTER.
That being said, without storyline spoilers, what do I NEED to know about the game play before I begin?
Definitely keep rebuilding Norende Village. Some of the best stuff come from there, as well as costumes if you're not satisfied with a job's costume on a certain character.
I recommend building the weapon and armor shops as priority. The weapon shop is relatively easy to build and contains the Angel Bow, a very powerful bow that is only outclassed by endgame items and you can get it early to midgame if you focus your efforts on the weapon shop.
The armor shop has some meh early items but most importantly has Red Cap, which is pretty good for pretty much all game. It's suited for physical attackers since it gives strength and agility. I mostly use this for the agility stat to get my attackers faster than my heal/support, the strength is a bonus.
Definitely get a few levels in the special moves shop (bottom right part of the village) for extra special moves.
As for the rest of the game... Just general tips. I recommend trying all the jobs. Each job requires points to level up, but at level 9 it gets much much higher all of a sudden. So if you get a job to level 9, I suggest trying something else just to mix things up and make use of job points. Chapter 5 is when EXP and JP rain all day, so you can max jobs there.
Stealing is pretty great for getting items one or two chapters early. But it's chapter 6+ when you really want to steal from bosses as some items won't be obtained in shops. You'll still get all of the items to complete your journal, but only in one's or two's. Steal (with Rob Blind support ability) to get more.
Money is really easy to make. Don't hesitate to upgrade your entire party upon reaching a new town/city. It could give the edge you need, especially against bosses.
Don't worry about sticking your characters into conventional roles. Their stats are very close to each other that in the long run, won't matter at all. Just decide on what you want to do with your party however it suits you.
If I remember anything else, I'll just edit this post later. Good luck!