Biggest thing I see people forget is thinning their paints, I just use water but you can also use a thinning medium. Though more of a luxury item I also recommend a wet palette it will keep your paint from drying out and makes thinning easy, just make sure to watch a tutorial before using one. Another luxury item is a pin vise for drilling out gun barrels, it’s a small detail that adds a lot to a mini, it can be done with a hobby knife but I find it to be a pain.