[Tamar]

Hello Jeremy

I think the best advice (and one that you are most likely are following already) is to pick an car, subject that you really really want to have, build and race for your first "scratch  build".

You would also need to define for your self what "scratch building" means to you.
My personal definition is that there's at least one item on the project that has been build from "nothing"
Can be as small as a different helmet, removing a bumper or adding a rear wing or just a livery that no one has done before, can also include a complete body or chassis.

The reason its best to pick a car you care about is because as you try and learn new stuff...scratch building will not be easy street all the time.

Second tip I can give you regards the tools you might need for your project.
As you mentioned Brushes...yes there are zillion types of hair, but for each type "penny wise pound foolish" still applies. Get the best quality you can afford.
The last thing you want for any type of brush is for a hair to come unstuck and lodge itself on your almost finished project.

with kind regards
Tamar