Masking help

Spray lightest colors to darkest is a general rule. Do the lightest color first, mask it off, spray on the next darkest color, continue as needed. 

its easier to apply a darker color over a lighter color than the other way around. 

pinstripe decals?

They used to sell decal sheets with solid colors, which could be used for stripes- have not seen them in awhile, but they may be out there.

To avoid jagged edges on masked areas, two things I recommend- one, use good modelers masking tape like Tamiya.

Second- seal the edges of the tape.  Do this after masking and burnishing edges down (I use Q-tips for this).  Then, apply another coat of the color that you are masking over.  This results in any bleed under at the edge will not be noticable, since the bleed through area is same color as the area masked.

I also find that at times if I'm masking windows or delicate areas, I will use the tip of a round toothpick to get into tight areas to burnish the tape down.

I too use mainly Tamiya hobby tape in various widths. I've also used 3M Blue Painters tape and FrogTape, when using those, it is typically for covering larger areas. If I want a super crisp line using the general masking brand tapes, I will use a damp (not excessivley wet) Q-tip to smooth down the edge. (I've been told that these painters tapes have an additive in the adhesive that reacts with moisture to seal...I haven't looked this up to confirm).

For me, I really depends on the paint. Typically, I'd spray the pinstripe, mask it with a strip of tape, then do the next color, mask that, and do the next color. However...if' you're using a metalic paint...those are weak and peel up with the tape pretty easily. In that case, I'd paint the first main color (lightest color). I'd mask that off at what will later be the farther edge of your pinstripe. Paint the next color. Once dry, mask over that, along the edge of the mask that's already there for the first color. Peel off first mask, and re-mask for the pinstripe. Spraying light coats will help to prevent seapage under the tape and give you a nice, clean edge.

Thanks for the great tips!

I'm going to experiment on a scrap piece first.

The main colors are Alclad Transparent Bottle Green and Gloss Black with the dividing stripes Model Master Copper, so it may be a bit of a nail biter.

What is best tape to mask with especially for thin fine lines, like pipes, cabling raised from smooth plastic surface. Like sub interior details? dgb

Jammydog sells masking tape in .75 & .5mm.  Otherwise I have to make my own.