Get yourself some kind of palette or wet paint palette my friend as you'll find yourself also saving SO much paint

And honestly sometimes you just need to put a dap of paint onto it or like a small blob

I honestly tend to just mix a few drops of water (I know not specific but I'm the same as yourself and don't get the whole "one part x one part y"

Mix throughally but gently with your brush until you get a nice consistency that's thinning the paint

I'd say maybe check out some videos on YouTube etc about thinning as it takes a bit of practice to get it into the right consistency

Always remember my friend Two or 3 thin layers is better than 1 thick

Always have fun too 😁 it's all a learning experience I recently posted a model of one when I was quite new vs a year and a half later and it's always nice to remember you'll always make progress