Eee, I as mentioned! Thank you. :)
I think that you are off to a good start, considering you have not being doing this for a long time.
My advice is to just try to fix some things up:
Gatrie:
The colour palette could be a bit lighter and a bit more vibrant but it isn't bad.
Gatrie is a tricky one since their is a large design gap between FE6-8 generals and FE9-10 generals.
I think that the best thing to do is make a shield to put in his hand, shorten the brown armour skirt things(I am not sure what they are called haha), take the trim off the breastplate and make some trim on it around the edges of it, and make the shoulder pads a bit smaller.
Mia:
There isn't too much to do with Mia without getting into new poses. All I can really see is giving the palette a bit more contrast and giving her long hair(normal myrmidon hair would suffice, though you can customize if you want) because she doesn't have a pony tail.
Tormod:
Probably the worst one. His colour palette is completely off(reference official artwork to see it), he is messy looking, and remember: Tormod is young so perhaps editing Ewan would be a better idea than the FE6 Sage.
Shinon:
My only problem is that Shinon has a short cape and not armour so you should probably edit the armour off and make a little bit of cape on him.
Jill:
The ponytail should be behind her and in front of the wing. At the moment it looks like she has a ponytail on the side of her head.
Also, Jill uses axes, not lances.
Ike:
I am not sure which Ike you are aiming for but I am assuming FE10.
If so, the problem is that his sword should not be on his shoulder and he is lacking his blue shoulder pad. It shouldn't be too hard to make that for him. His cape also is all red with no trim.
Volug:
Nothing I can say here, it is just a recolour.
Lucia:
Main problem is her colours; they're creamy atm.
Her colour is white so when making the palette use a relatively dark grey for the darkest shade, a light-medium grey for the middle shade, and an almost white for the lightest shade.
Tip: I find giving the grey a tint(I suggest blue for her) makes the colour much more interesting.
Rolf:
Rolf is fine but I do believe he has white armour, not brown, and he has a smaller bow than that.
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I hope you find this helpful and keep on trying. :)