As others have said:
Use intuition, similar to how you'd solve the F2L on a 3x3.
I'd say the most important part of a solve in regards to speed would be the look-ahead, like on most puzzles. Particularly with the megaminx, look-ahead is quite important because there are quite a few pieces that can be on all sides of the puzzle, and they can be difficult to find on a megaminx. But with practice, you'll be able to find them quickly. Watch some of the sub-minute videos for some inspiration.
Good luck.