Basically the only use they have now is saving your character from getting the XP for the promotion level.

Leveling Meg up is a waste of time.  She takes way too much BEXP to get to a decent level and you will have plenty of characters more worthy of that BEXP later.  Fiona and Meg are the two characters that you should basically forget about using, not because they suck later but because they use up too many resources to get to a level where they can hold their own.

BEXP is basically best used in the last 4 levels of each tier (17-20).  You want as many +1s per level as you can get and when your characters start capping out some stats, they tend to get only one or two +1s in those last few levels.  This is where using BEXP and always getting three +1s will help them cap even their bad stats that normally don't see much increase.

Also, I hope you took Sothe's weapons away from him when you started.  He's already promoted (tier 2) so all he does early game is suck XP away from units like Micaiah and the rest who desperately need it.

Ah, Meg. Forgot about her. I always fought she was the most useless FE character ever, but in Shadow Dragon there are at least 10 that are worse, lol.

Seriously, listen to WoW. I only used my (insane amount) of BEXP before the Endgame and it worked great.

And indeed, be careful of the Jeigans. Sothe is not really a Jeigan, only in Book 1. He becomes really good.

Word of advice in any FE game. RESET is your friend. FE games are known for being insanely tough and tougher later on in the game.

Some characters like Meg and Fiona must not be used ever (maybe on easy setting). Leonardo and Aran are pretty useless later in the game, but you should keep them somewhere between 5 levels below the main party or you will have a very tough time in Chapter 3. Jill and Edward are beasts, level them up as much as you can.

"Jill and Edward are beasts, level them up as much as you can."

I liked Zihark and Haar much more. I think they both made the final party. I'm sure of Haar, because only then his weak RES came to light.

Haar is almost as good as Jill. Jill ends with better stats (with battle xp she will cap every important stat). Jill also has a better accuracy than Haar. Haar is lot easier to train, but he is not avalaible as much as Jill, so Jill gets to S and SS weapon levels much earliwer than Haar. Zihark is only good if you use Bexp or get a good RNG. Edward will always surpass him in the same level (for example 20/05) and his stat caps a little higher. But Zihark comes with better equipment and higher levels. My final party had both Jill and Haar.

Another tip, try to use steel weapons or higher as much as you can (they give 2X the normal xp as iron weapons). I would use iron a lot because I though that dealing less damage and attacking more would earn me more XP. However 3 attacks with a iron weapon earn less than 2 with a steel weapon. Also, save those arms scrolls for rank B or higher.

That's good to know, higher lvl weapon give more weapon xp. I thought it was per use even if it was a miss, since I did get weapon level up during a miss.

I like pairing Nolan and Leonardo so far. Picking up or weakening enemies with Leonardo and then using Nolan to kill off without getting counter attacked.

In chapter 1 you can unequip Sothe`s weapon (so he doesn`t counter) and use him as a bait/meatshield. Later in the game use units with high Def (Aran) or high HP (Nolah). That is the best way to lure strong units without getting killed. For mages you can do the same with units with high RES (mages and bishops). If it is a very long range spell (in a way you can`t get to the mage in less than a turn) just let a mage in attack range and heal every turn with someone outside the attack range. Wait untill the scroll breaks and advance.

Leonardo is the worst archer in the game so don`t get to attached to him (but don`t let influence your game, play the way you like).

When you're playing, do you feel them devs played through the same level over and over and over and over to refine the level.

dev1: Okay, I think this level is done. Let's move to the next one.
dev2: Wait! I think it's still too easy. Let's send reenforcement and attack them from behind as they reach the boss.
dev1: Wouldn't that give them too much xp for extra kills?
dev2: Not if we send flyers in to flank their ranks and kill of their weakling casters.