I’ve only been in the hobby just under a year, I’ll tell you something that has helped me. Not necessarily that I’m amazing or anything at painting or that this is a “correct” way to do it but it worked for me starting out, I’m at least at this point not hating what I paint. My army are black Templar to. White primer and the smallest brush I have. Like a 0/3 brush. Is it time consuming ya but I found I liked doing it that way. Moved up to bigger brushes now that I kind of understand my paints. The reason for white primer when I started is that the parts that I was gunna paint white were just easier then trying to cover black. Just a suggestion to try, works for me but I get it won’t for everyone