I have been using a base layer, camo spandex top and bottom, then put my 3-D suit over that. After every single hunt I strip down, shower and check myself for ticks... haven't found a single tick yet! (knocking on wood!) Chiggers, we don't have here.. When I was in the army, guys would put (laugh all you want.. it worked!) knee high women's nylons on under their socks. It kept chiggers off your legs and it helped with long marches as you feet wouldn't slide around as much and give you blisters. Nothing sucks more than blisters on your feet while you are marching everywhere.
Giant vote for Sawyers Spray. I will not go into the woods anymore without my clothes being treated. Where I live the tick populations have exploded and they're bad, really bad. Permethrin spray (Sawyers) works like a charm to repel those and pretty much any other insect. The best part of Permethrin is that it KILLS ticks, not just repel them. As for getting it on your skin. I don't know. I've gotten overspray on my hands plenty of times while treating my clothing. I just wash up afterwards and never have had an issue. Now inhaling any of it is a different story. Its nasty stuff. Do it out of the wind so you don't risk sucking any of it in.