^ a little late on the reply - apologies; there are some decent tutorials type videos on youtube for this - as well as by Star Wars enthusiasts such as RetroBlasting (who often fix / restore some of the old toys and models etc).
There also seems to be a few on ‘weathering’ various Star Wars toys and models - I have to admit the effect for look superb - and can make even a very cheap looking toy look like it’d pride of place in someone’s collection. Someone on here (canofhumdingers? edit: it was joefavs - here) they did an awesome paint job on a cheap-looking plastic toy Han Solo blaster - it looked superb, just like an expensive replica, when he’d finished it.
When I was younger (and had better eyesight, a steady hand and patience!) I’d practice on all sorts of cheap or damaged airfix models to try and ‘get my eye in’ or be ‘in the zone’ - before moving on to actual model I wanted to try and get ‘just right’. The paintings still weren’t great - but were better for the practice 😃
The RetroBlasting youtube channel (by OT•com member nohandluke):-
https://www.youtube.com/user/retroblasting/videos
His ‘Star Wars Follies’ series (especially with ‘Broken Vader’) is a lot of fun 👍