yeah, when I am doing a metallic color like that I do what I suggested above for the primer (no need to tape since you're brushing). Then, before I spray the color I tape off about 2-3" away from the area, and use a piece of thin carboard as a blocker while spraying holding it (the cardboard) maybe a 1/2" away from the body...this way you to get enough paint on the area you want it, and a light overspray about 3" out around the area. Gently watersand and compound the whole area to cut the overspray back off the 'good' paint, then mask like 4" out and spray your clear using the same technique.
It'll never been *perfect* but I've done some where you'd be really hard pressed to tell if you didn't know. Maybe next time I'll do a video or something because it is really hard to describe without seeing/showing. It is a super time consuming process though, and you need the vehicle essentially off the road and somewhere dry for at least a few days....which can be tough.
Edit: What I'd do with yours since I assume you've sprayed primer to the tape line, is remove the tape, and wet sand (use something like 1000 grit, maybe 800 if you're daring) the primed area carefully to knock down the ridge you're going to have at the tape line. Use a small block (I like to use a standard white eraser) with your wet paper and do your best to keep it on the primed area. Should be able to smooth it out like that...ideally, you want the entire primed area flush with the 'good' paint. Then mask a little further out and do as a described above with the color and clear.
Good luck! I find body work like this interesting because it's a challenge, but rewarding when you get it right (for me at least).....but also very frustrating when it doesn't go your way.
