I'd be more than happy to share my techniques for washes. I've had quite a few people ask me the same. I don't think my technique is all that special, but I'm happy to help out anyway.
There's probably a few key things that ensure a good result.
1. Nice deep recessed detail with sharpish edges to "hold" the wash in there. If not deep enough then deepen with a scriber.
2. Good smooth glossy surface. If you have this sorted the excess wash is easy to remove with a dry or slightly damp cotton bud. If you have areas of dryspray or rough texture then these areas will take your wash and spread it out like a stain and will be really hard to remove. I'd say this could be happening if you're using TS-13 which is a fast drying lacquer. (this is more a technique thing than anything else, and even more difficult when using a spraycan)
Your choice of gloss clear isn't really that important but you need to find one that allows you to achieve a good uniform gloss.
3. Mix Ratio of wash mixture.
I use Tamiya flat acrylics in the round large bottle.
1 part paint first (a colour to suit - very rarely black)
1 part water next
1 part dish detergent last (cheap and nasty is ok)
The detergent lowers the surface tension of the water and encourages flow. It also retards the adhesion so excess can be removed. Experiment with it a bit, the wash needs to flow but be able to give good colour depth in one hit. The wash will sit around raised detailif you apply correctly and require very little clean up.
The advantage in the flat paints is that they are usually more pigmented than gloss paints. This gives better opacity and when the wash is dry it will be flat, so you know when you can remove the excess. It is best removed when quite fresh. Remember of course that the more you apply the more you will need to clean up.
4. This type of wash needs to be made fresh for each session. It doesn't keep well.
There are many varied ideas on washes and materials. These are just what I use.
I hope that helps you a bit Dave. Best of luck.
Keep the Blue Side Up !
Andrew P (A1)