Seriously, I can’t even use cotton strings without feeling like they’re going to fly off. I think my fingers are too tapered at that end, with the last knuckle not having enough of a “bump” for comfort. I mean… COTTON strings for crying out loud!
I have grown accustomed to using a finch head knot, and I’m uneasy any time I use a regular slipknot these days.
Here’s a video of two methods. It’s not as clear as I meant it to be, but if you try it out instead of just rewinding the video a bunch of times, you should get the idea of how to tie it right away.
http://www.youtube.com/watch?v=cSKKgrvcPgw
(non-embedded: http://youtu.be/cSKKgrvcPgw)
It IS tighter, it does NOT give you any slack, and it IS less comfortable. Especially until your fingers toughen up a bit, you probably want to wiggle it loose every now and then or give your fingers a break. Don’t let them turn purple and explodez blood vessels or anything. 
But once you get used to it, it’s tough to go to a slippy, flippy-aroundy slipknot.