I flew models for about 14 years before I was able to land in a slip. Actually, it was flying lessons that helped me get the technique down. I highly recommend taking a few lessons, particularly in a tail dragger.

Many of the sims, like G2 will allow you to program a cross wind and practice slipping.

The all time greatest plane to learn slips has got to be a Cub ! You probably can't have any more fun than landing a Cub in a mild crosswind.

I consider landing in a slip an advanced manuever. Its easy to get confussed and there is little room for error. I don't recommend it for beginners.