hey jenny.
i used to have the same problem. lately, however, i haven't seemed to have any ingrown hairs. a few things have changed so i am not sure what exactly did the trick, but here goes -

1. i started using that "triple action" razor.

2. when i think i need to shave i will usually wait an extra day or two after that then shave.

3. the areas in which i would seem to get ingrown hairs most often i would grag a washclothe and give it a "little extra" scrub to make sure that there isn't anything blocking - like your own bodies oil etc...

hope this helps.
boz.