Try to imagine a shape you like to make in 3D. Can you see it clearly in your thinking or is it only a fuzzy dream with no exact forms? If it's clear and stays stable you have a good possiblity to draw it - maybe slowly and inaccurately if your hands are not trained. It's the same on paper and with computer programs. If it stays stable in your mind you finally get it copied out. In a computer it can happen even without actual drawing, you define the forms as combined idealized shapes such as arcs, lines, bezier curves etc...(=you use vectors in a program like Illustrator or Inkscape)
An extreme possiblity to output it from your head is to write commands. Many programs, 2D and 3D , have a command line mode. OpenSCAD for ex. is used only via command line interface. The program shows - not what you drew, but what forms you told it to create. I bet in practice this must be limited to engineering like works, no rich game characters will come out this way, because the needed commands would fill a bible sized book.
Creating a shape in one's mind and keeping it clear so long that one gets it drawn is a remarkable talent. I bet it's the same as a good music composer has if he imagines his music and then writes it onto staffs. Other composers play this and that into a recorder and finally via trial and error they can get together something usable.
I can earn money by doing some tiresome not so creative works, but as a creative artist I feel I am only a lousy hobbyist. I must draw a shape at first coarsely, then try to invent more details to it and soon the original idea may be totally vanished, but I still have got something. Drawing is the only way to get something together. I must have a fast method to draw. Pen and paper are excellent for this purpose. From paper sketch I can copy what I got into the computer and remake it with nice smooth curves and perfect angles. As a replacement of paper I can use a drawing tablet, but paper needs no electricity and I can always have a piece.
If I can see the wanted form in front of my eyes when I draw (=someone has already created it) or it's something simple geometrical, so simple that I can define it as memorizable sentences, for ex. a cube, and a pyramid on its top, I do not need paper sketches. I input it to my computer directly.
Of course a talented artist may have created so complex forms with so many and fine inter-relations that I do not catch them right. My copy will at best be a laughable caricature. I can see the result is wrong but I can't fix it because I cannot see what is the essence and I'm not skilled enough to make an exact copy like a scanner. But if it's a rectangular building, it more likely will be copied perfectly. I can even remember it as a set of sentences, if it's not too complex. Or it can be complex, but the job doesn't need fine details at all.
Stepping into 3D is useless if 2D works aren't succesful. Why? In theory there could exist a blind born sculptor who makes perfect sculpts, but never draws anything. Of course he must stay within the resolution of his hands, there cannot be any millimeter sized designed details. In web you can find blind painters and sculptors, but those which I have noticed, became blind as adults and have built their model of the world as seen images.
I guess: Because our computer tools are 2D, you must have good 2D recognition and output to be able to interact with the computer bidirectionally in 3D works. Only in those cases, where you use preset geometric forms or modify them by scaling, rotating, bending, making intersections etc... you can work efficiently without being able to draw. That means engineering like creations, not anything as rich as human or animal like characters. It was the same in 2D.
The drawing tools to start with? I say nothing is better than a pen + paper. It obeys exactly your hand movements. The problem is only to develop those movements. It's visual recognition, coordination, pure knowledge how to present relations with lines and shadings and, of course, the imagination behind all. If your movements are limited due injuries or an illness, but you believe you have what's needed to have between the ears, take a computer.
Nothing prevents to use computer in parallel with the pen and paper, because using computer tools succesfully also need a lot of practicing. But with pen you can draw anywhere the needed thousands of sketches to develop the needed basic skills - coordination and the processes between your ears. Get some books about drawing. From there you can pour the needed knowledge easier than only by watching already done works and experimenting.
With a computer your time more than easily gets wasted with playing with tricks and trying to find shortcuts around still missing coordination, recognition, knowledge and even around missing imagination.
