When I lay down the decals, I use a number of products-----Micro Set, Micro Solv, Solvaset or Mark Fit. I just make sure those decals are down very well and DRY, then I give em a couple light coats of clear. I sand the area to be masked with 800-1000 and when I finish masking, another light coat of clear over the masked area. This helps seal the edge of your tape and helps stop some of that paint bleed. I also might mention to invest in good quality masking tape. I suggest a high end 3-M or Tamiya masking tape. Yes, you pay more but if you want good results, stay away from that dollar store look-a like tape, it will do nothing but make you upset. Last, DO NOT RUSH and take your time and keep things clean and neat, keep a tac-cloth around and use it. And if you are wondering, I have had good luck with Testors Clear but I usually use only Tamiya TS-13 or Mr. Hobby Clear. Test these clears and setting solutions on cheap kit decals first, (AMT, MPC, Revell) sometimes they do not play well together. Usually a Tamiya or aftermarket decal is made for this stuff so you are good to go.