It's just a personal thing, but I really don't like roll out skills. Many people find them just as safe as any other skill, but I just don't like them.. never did, don't think I ever will.
My suggestion for development, put a spring board in front of a porta-pit, and do fronts that you land upright. Easy. Put on another 8" mat, same. Should still be easy.
From there, move the spring-board in front of a spotting block turned on its side, so, roughly a front onto mats 2' or so above the ground. Behind the spotting block, but a porta-pit. Do a front onto the spotting block (or mats), punch dive roll into the porta-pit. You should land with your hands at your side, leaning forward a bit, and lift (your arms) them as you punch. This should significantly slow your rotation, and you need to feel that. In my opinion, ideally you should land on the spotting block in a "hollow" position with your hands at your side, leaning slightly forward.
From there.. it kinda depends on your comfort level. You should never land head first into a pit, so I don't suggest throwing them into a pit... though you could stack some resi's up in the pit and throw them onto that... otherwise, you just take out the spotting block and your front off the spring board should be high enough to do a 3/4 into the porta-pit, or try one on the tumble track into a porta-pit.
This is a potentially dangerous skill. Take it slow, and practice it often.. using a firmer 8" mat to land into would be better than a soft one, as the softer 8" mat would absorb more rotation and put pressure on your back in places you wouldn't want pressure.
ideally (in my opinion) you should be capable of doing a front and "standing up" in air about 2' off the ground before you go for the 3/4. Tossing a few doubles into the pit or off a tumble track would do you a world of good as well to develop the air sense you're looking for (and, I think, safer).
First of all, you need to have superb aerial awareness to even consider trying this skill. If you don't know exactly where you are in both a single and a double front (into a pit is fine), don't even think about a front 1 3/4.
The way I learned, and the way I would teach it (if I were to actually teach it to any of my students, which I have never yet felt any need to do), is by starting with a double front to your back into a pit or onto a resi. Do a ton of these; the goal is to get it to the point where you can comfortably spot the landing before ducking your head under for the second flip. From here, you can essentially train it as if you were doing a 1 3/4 on floor, but roll over to your back before you actually land. REMEMBER: IT'S NOT a 1 1/2 -- IT'S A 1 3/4. It does not go down head-first, it ducks under to your back, and it is much safer to overrotate the skill than to underrotate it.
Once you've done about a million of these and can comfortably spot the landing before ducking your head under, try it on the softest mat you can find (ideally a resi pit or something similar). Again, start the same way; overrotate it until you're comfortable, then open a little more and a little earlier until it turns into a nice smooth roll.
Once you've developed the necessary awareness for it, it's not all that hard and is loads of fun. But go conservative on this skill; if you mess it up, you're dead. And I'm not exaggerating on that.