Disclaimer: I've never played Fractal, and I'm still a Noble player myself. Most of my diplomatic experience is with Vanilla. Take any advice with a large dosage of NaCl.
Well, if you're Isabella, your best bet is probably to play to her strengths - religion. Found at least one early religion and spread it around, especially if you have neighbors on a continent. Since this is BTS, shoot for Theology and the Apostolic Palace ASAP. (I haven't done diplomatic much outside of Vanilla, so my UN advice isn't worth much here.)
Choose your friends wisely; don't buddy up to Montezuma, for example. Depending upon how many opponents are nearby (and how many of them succeed in founding their own early religions), you can probably tell who's going to be a problem or not. Also, never underestimate the power of sharing a war against a common foe; significant diplomatic bonuses there.
You'll also want to keep a vigilant eye on the Foreign Advisor screen. Know who hates who, and avoid trading with someone that your friends hate. Sometimes, trying to have too many friends can leave you with none. Remember, you're not trying to befriend *everyone* - you just want to have enough big civs behind you (but not bigger *than* you) that they'll support you in a diplomatic election.
Oh, and if you get a request of "could you spare this for a good friend?" think twice before telling that civ to shove it. -1 for ignoring them or +1 for helping? Depends on the tech they're asking for.
That's about all I got; hope that helps.
