As
meatybtz said, buying expensive brushes does help incredibly, I picked up some Series 7 Windsor and Newton brushes and while I don’t use them for everyday use (I have some cheaper nail art brushes for that) when I need to do some detail work or something that requires some patience and a good flow off the brush, they are invaluable.
So long as you remember to clean them, put the protective cover back on and then put them back into the case you’ll have a brush that will serve you well for a long time!
Having the right paint helps too, check out the store if you’re interested or swing by Tale of Painters and check out the review there where Garfy did some fantastic edge highlighting on a Dark Angels Primaris Marine as well as a great write up too!