I’m assuming that you mean your right hand (for a right handed player). The simple answer, as Dad says above, is practise, pace (start slow) and patience. When I took lessons as a young boy, when dinosaurs walked the Earth, I was taught arpeggios and pattern picking and I still have those under my fingers 50 years later. However, anything that doesn’t fall under those ingrained patterns has to be practised over and over to get right (yes, you, Jimmy ‘bloody’ Page! I’m looking at you and your weird, ever changing patterns in Bron Y Aur). My point is, the actual mechanics don’t really become much easier, you just know that these things take time, better than you did when first starting out.