Amen brother!

Seriously, it just takes practice. Most people find two things hard about a slip:
1. moving the hands in opposite directions at the same time (often, moving both sticks "out" is easier than "in" or vice-versa, but cross wind landings don't give you a choice, so work on both)
2. holding the sticks off center for a good length of time, and making small adjustments while holding the sticks off center.

I'll still botch a slip once in a while, but usually when I'm trying to do something extreme (like the one-wheel touch and goes, rolling most of the runway on one wheel before lifting off stuff), not when I'm just trying to land. Most landings don't require nearly that much slip, even short or obstructed fields.

(One of these days I'm going to out fit an LT-40 for serious STOL action.... As it is, we've marked out a 100' foot box on the grass runway, and I can get up and down and back up with out ever touching outside the box (sometimes))