While I agree that it is best to try and find your own balance there are some simple things that you can do to get started on finding your way.
If this is a RT relationship talk lots, discuss things that you both enjoy and discover what the limits are for both of you. In the BDSM world perfect matches are even rarer than in the vanilla world, with so many kinks and so many different level within each finding a partner who enjoys exactly the same things as you is pretty unusual. If this is an online thing its a similar process, use voice chat if possible but make sure you get to know each other.
Tip for the Dom, start slowly, go easy, you can always get firmer, harder or tougher but if you start out too harsh its hard to take it back and you may have put your sub off that activity.
Tip for the sub, keep communicating, use your safe words (makes sure you have a "slower/softer" word as well as a "stop") to help guide your Dom.
That said it is not uncommon for the Dom to be unwilling to push his sub so there too you will need to guide him if he isn't challenging you enough.
And finally research stuff you're interested in trying. Some activities have elements that can be dangerous so make sure you find the safe ways to play.
Hope this helps a bit...
