Ahh Ryu, the original guy in the karate uniform stereotype leading role. Ryu was awesome back in Street Fighter 1 and now is way awesomer in Street Fighter 4. If you disagree, he can Shoryuken your ass anyday.

Ultra is one tough looking SOB and only noobs throw Ultras without setting them up. Today's post shall discuss the various ways of Ryu's Ultra setup. Keep in mind that there aren't any such thing as Ultra cancel. Ultras aren't cancelable unlike Super.
2 main methods of setting up Ultras:

1. When the opponent crumbles to the floor after being hit by FA
2. Air juggles
   

Of course, we will get the obvious out of the way which is:

FADC(Level3)xxMetsu

Yes, that is the general formula to setup for an Ultra for everyone and falls under category 1). I will only display a minimum hits combo since it is practical in real matches and also do-able using a PS3 controller. Besides, due to the damage scaling in SF4, it is sometimes unwise to do a long ass combos. And yes, I am no expert, just a very good novice.

Keep in mind that FADC-ing moves would take up 2 Super Bars and EX moves would take up 1 Super Bar. So, use it sparingly.

If the opponent is on the ground:

1. ShoryukenxxFADCxxMetsu
   
2. (corner)EX HadoukenxxMetsu
3. (corner)EX TatsumakixxMetsu

If the opponent is in the air:

1. LP ShoryukenxxMetsu
2. J+MPxxMetsu

Of course, one can expand these combos and create a complicated long string involving linking and canceling. For example:

J+HKxxF+HPxxShoryukenxxFADCxxMetsu

It takes more skill to pull it off and gives more damage, however, in order for me to execute the above mentioned combo during a heated match is a bit difficult. One of the flashiest combo that Ryu has is:

J+HKxxC+MKxxEX TatsumakixxEX HadoukenxxMetsu

Anyway, good luck of trying them out. If you'll excuse me, I've got myself some ass to kick. Metsuu Hadouken.