I like to play recball and woodsball so wenever I get a gun that is shiny, I give it a decent camo paintjob. It takes some time to get it to look right, but it works. I also custom paint my hoppers and masks. I have a Prodigy as a back-up marker currently and it's WAAAY too shiny. But I didn't feel like painting it because it looks too nice as it is. So I bought a guille kit and made a guille gun rag for it. The second link in my sig shows the marker with the gun rag on it.
That hardest part about using it is just getting it attached to your marker so that none of the moving parts catch it. I'll probably have an easier time putting it on my mag with no external parts moving (awesome technology).
I was thinking of making a guille vest or headpiece. But I get sooo hot when I play in the spring and summer...I'd never end up wearing it. I have a nice woodland camo long-sleeve shirt that I never wear just because I get too hot. I can't even paint my arms because I sweat so much that it just makes a mess.
For my mask, what I did to make it more camoflaged is not only give it a little paint job, but also buy a woodland camo headwrap and then cut it in the back (otherwise it isn't big enought to wrap around the mask). I then tie it to opposite sides of the mask to keep it on. It does restrict the peripheal vision a tad...especially if it starts moving around...but the mesh is see through so it doesn't totally restrict it.
I agree that you shouldn't use a guille suit and expect to be invisible. You definitely have to learn how to be stealthy and use tactics.
Lesson 1: Be patient. Unlike speedball, you don't need to just fly forward off the break. Know the field...know the boundries. The boundries can be you friend (with your back to the boundry, there's nobody behind you). Try and work your way around the opponent or to their flank. Use the camo to move around and not be seen. But be patient. There's no use using a guille suit to get to a good position on your opponent only to fire at him to soon and give away your position. No matter how good your guille suit is, once your enemy knows where you are, it's somewhat useless. Remember that the goal of paintball is not only to kill everyone else, but also not to get killed yourself. Let the anxious 10 year olds with their Ions go up to the front and kill each other...get in a good position...then start taking out the survivors.
I'm not advocating hiding...paintball can get very boring if you're laying under a guille blanket for 15 minutes. Just don't move too fast...don't give away your position to early...be patient...and make your shots count.
And even if you make a really bad guille suit or gun rag...or even if you just wear a camo outfit...ANYTHING HELPS. All you need in most cases is to have just enough camo that the enemy won't catch you out of the corner of his eye. Don't expect to be invisible. Unless you're a special ops marine...you don't need to be invisible. Use camo/guille to just give you a slight advantage. Like I said, I have the gun rag and a camo mask...camo head to toe...but I wear a short sleeved shirt so my arms are totally visible. I would rather be comfortable than invisible. I have camo mesh gloves which are really nice because tehy breathe well and at least keep your hand somewhat camoflaged.