I have Realflight G3.5. I turned down the Physics speed to about 30% and practiced there over and over. Once I got those down, I sped it up in 10% increments until I got about 120% physics speed and could keep up. Then I turned it back down to 100% and practiced them with just about every 3D-capable plane on the sim. I then went on to doing slow rolls and rolling circles and stuff. Everyone told me I learned in the wrong order...but rolling harriers just look so much cooler than a slow roll, I had to learn to do them first! The only other tip I can suggest is the one you'll never not hear: practice 'till your thumbs hurt.