Fantastic first serious attempts, very neat and good colour choices all round.
Maybe trying to just leave a bit more dark showing or even going back in
with a thin line of dark brown / black paint along the joins between parts
would help deffinition .
For example of what i mean I'll use your top picture, Where the brown of
the waistcoat lies against the white of the shirt, a dark defining line between the two will really make the definition stand out and start to bring
the figures to life, I have just put in a few lines of black on the picture
with an art programe ( which I'm not as good at using as a brush ) under
the collar and around the shoulder for example .
I think you can see the difference ?
If you start with a black undercoat base and get into the habbit of leaving
this thin gap between layers it will show you good results very quickly.
other than that TOP JOB keep it up !