If you are talking out of run, simply crouch first and then do the tilt. D-tilt is easy since you just crouch and hit A. U-tilt and F-tilt you don't get to buffer the direction, and thus you must do the tilt by pressing the joystick only slightly in the direction needed. F-tilt is hardest simply because if you press too far it will go back into a run and you'll do a dash attack like you said.
The other easy (relatively) option is to wavedash into a tilt, which you can do out of a run or dash (or standing). When you have the option of crouching, wavedash to tilt is the slower option, but it's also the option that allows you to retreat just before the tilt, and many would say it's easier to space well. So there are pros and cons to using each method even when both options are available.
The hard option is pivot tilting which can only be done out of a dash. Basically during the turn around animation when you change directions during your dash, there's a frame where you are considered standing, and you can do any move from here. This is very hard to time consistently. I really only use pivot with Marth's f-smash and that's partially 'cause you can do it as part of a combo and thus muscle memory can make it easier. I have trouble doing this on the fly. Character's with fast, long ranged f-smashes might use pivots, but pivot tilting is so hard it might not be practical. I used to pivot f-tilt with DDD, but I had to set my c-stick to Attack which is somewhat buggy and probably not worth it unless said bugs get fixed.
c-stick set to attack pros: You can jab/nair with diagonal c-stick. You can f-tilt or jab out of pivot and crouch out of run way more easily. Up-c and down-c are still smashes.
c-stick set to attack cons: You can't up smash out of run/dash with the c-stick (unless you manually hit jump first). If you mistime a c-stick input and quickly re-input the c-stick at the right timing, the second input will be ignored. In fact, if you repeatedly mash c-stick all inputs but the first are ignored. I'm not sure if this would affect the dual-stick smash DI tricks, but it's very likely. If you do falling up-air to up smash with your character using c-stick both times, the up smash will probably won't happen.