My experiences with the RNG has been rather different from most other people, so what worked for me may not work for you. Like, in both of my playthroughs, my Lilina was RNG-blessed and capped Magic, which is to be expected, as well as Speed. She murdered everything, just had to be careful that I didn't expose her to any physical enemies. Lugh ended up sucking big time, he was a slower and MUCH weaker Lilina, 10 Magic at 20/1!; his entire role was backup staff duty. Alan was Speed screwed, and Lance picked up mid-game and carried me through the endgame as my best Paladin. Gonzales took a bit of training, but he ripped through hoards of enemies with Killer Axes. Rutger was RNG-screwed pretty bad and couldn't deal any meaningful damage, even after promoting. Fir, on the other hand, I trained her in the chapter I got her and she was one of my deadliest units, Strength turned out great. Miledy and Dieck, of course, were fantastic. Armour Knights are awful, I really tried with Barthe but he just couldn't keep up.
Other than those anecdotes, my best advice is to keep a brisk pace. The maps are huge and many chapters are on a timer, so it's best not to dawdle. That's sometimes easier said than done, with massive amounts of reinforcements and promoted enemies showing up fairly early when compared to the other GBA games. Just plan accordingly, spend a decent amount of time reviewing the Preparations screen. I also found it helpful to keep track of my weapons and other supplies with pen and paper. I'd keep an ongoing tally of which units I use and what weapons they take, which made buying and stocking weapons easier. I find money a bit more difficult to come by in this one, so I will admit that I've arena abused here and there to save up cash for things like Physic staves and Killer weapons.
