I have to say I'm good solid intermediate playing level and I 've come across a little issue. I've played using a thumb pick only for the last two years (got a thumb pick craze, I guess), and know I'm trying to start using normal picks again. Problem is, every time I use a normal flat pick, I hear way too much of the pick slapping against the strings. I've tryed using heavy picks and light picks and they both do it. I do alot of strumming and singing so It's very annoying. For some reasin the finger picks don't do that. I can't play happily with a normal flat pick anymore.
Try thinner picks, perhaps?
play with a flat angle, instead of using the edges of the pick.
or get softer picks. there are some made of materials like nylon that are a lot quieter. you might also try very heavy picks - i make less pick noise with a 2mm or 3mm pick than a 1mm or lighter.
I found that if you hold your pick tighter, and kind of pull it in more, so your holding onto more of the pick, it stops the slapping noise, but it takes a bit of getting used to. Personally, i dont mind the slapping noise too much, mainly because I strum with my fingers because I prefer the sound, but just be careful when your holding it tighter because it makes a louder sound and if played wrong it can sound quite ugly.