NiGHTS into dreams...

There's a fairly easy way to get this achievement if you're having trouble doing enough tricks (11). Once you go through one of the blue and yellow rings, fly up towards the "roof" of the level (a slanted part works better), fly against it and mash LT/RT. You'll do the tricks but there'll be next to no animation for it so you can rack up tricks faster than usual and get a DREAMY rating every single time.

This is also great for A-Ranking missions if you're struggling with that.

(Hooded Claw 006 noted that mashing LB/RB is a little faster than mashing the triggers, so you can make this method even easier if you're still having trouble. :) I managed to do it a couple of seconds faster doing it this way.)

This is fairly simple. Go through an acrobat ring ( blue and yellow) and once you have a yellow ribbon trailing you spam the L and R triggers to do tricks. If you can manage 11 tricks before the acrobat ring wears off, the achievement is yours.