Yeah, for vaseline/cotton balls you don't want to saturate them all the way through. Coat the entire outside and work it in just a little bit.
When you want to light one you tear it open so that alot of the dry interior is exposed - this is what catches the spark and then acts like a wick - drawing up the petroleum and allowing it to burn. Essentially it's a mini oil lamp.
It still works when the ball is totally saturated, but then it requires alot greater heat source to obtain ignition.
For char cloth I prefer denim and my 'secret' is to stuff a cannister with scraps of cloth, close it up, poke a hole in it, then drop the whole thing into a bed of coals. When smoke starts coming out of the hole light the smoke so that it becomes a flame. When that flame goes out remove the cannister from the coals because it's done. Cannister with a large surface area to volume type of shape seem to work best.