Hmm. . . toughie. I made the jump when warlord was too easy.
The thing to keep in mind is that all the bonus' you had against the AI are now gone. You will research as fast as the AI, and they will build as quickly as you. So it's basically even footing.
Read Bamspeedy's Deity Settlers in the War Academy. That's probably a pretty good place to start. When you can be pumping out a settler ever four turns, then you'll be able to expand quickly. I would also set up a Worker Factory, and a Defenisve Factory, where you can spit these units out as fast as a Settler.
The AI is going to be a bit more aggressive, too, so you're not going to be able to send those settlers out unescorted as much, nor leave the cities empty. It gets much worse higher up, but you can still get away with it some in Regent.
And don't be afraid to step back, either. Jumping to a new level can be intimidating. When I went to Monarch, it was OMG! Now monarch is a touch to easy. But I'm not that fond of emporer. . .
If Regent does seem to much, one thing you can do is get into the editor and make a Semi-Regent level. This is where you put the difficulty somewhere between Regent and Warlord. I've done this, and it's been a bit since I've done it. I'll have to dig the file up and see what I did, then I'll post it back here. I think I gave the Ai extra units between the two levels (say, if Regent gave 2 settlers, and Monarch 4, I gave them 3. And I'm just throwing numbers out, not saying that's what it is in the editor.). And the AI to AI trade rate was tweaked, as well as the AI production bonus.
Hmm. . .now that I'm thinking about it, I may do that with Emporer too.