practice, practice, practice. learn all you can about a program and keep learning it. get books about the programs, take classes at a college. if you have the time the more you learn about the program and keep using it the easy it is to create in it. but first you have to deciede what program you want to use. I know off the top of my head there is solidwork and pro e and auto cad. Ive used proe I like it kinda hard at times. its the most powerful, Ive heard solidworks is really good too, autocad is ok for 3d cad best for 2d tho. just take ur time and pick a program and leanr it.and getting frustrated is part of the game. cuz soemtimes it doesnt always render the shape how you want it.