here is a copy of what my style sheet looks like, am still new to css so apologies for messy code.
It really just takes time and experience to get it to work… one thing I would recommend is validating all your code – making sure its as valid as it can be then working from there. Sometimes validation wont fix all your issues, but it will make a good start…
Other than that I would just Google for cross-browser tips, and keep going! you have done great to get this far, so done stop now :)
Continuing what Rob suggested, another way to combat some cross-browser issues, specifically with IE6, is to use some scripts.
While I normally try to keep my websites as far from uneccessary scripts as possible, I’ve found one that has seemingly become invaluable to me. That is the ie7.js from Google (or at least Google hosts it, I have no idea if the person that wrote it actually works at Google).
Simply plop this into your <head></head> and you should have significantly less problems in IE6!