It's looking nice! I'd recommend using a type font instead of writing your letters by hand. Writing by hand is very tedious when writing a long form comic and if you use a type font it means that your text stay legible.
There's a nice free software called firealpaca that I think you might find useful, it has some nice features for comic making. In this software you can put a 'clipping' layer above your line art and change the colour of it. I think this could help in some places like Carlos's trousers or Neill's hair.
This is just my personal opinion, so you can take it or leave it, I'm just an amateur myself! 