One of the most easiest ways to make your vehicle fly is to spam B. Pressing B is suppose to flip your vehicle over when its upside down. But if you spam it on any vehicle it will start going up. I use it in the campaign a lot.

Basically you place a bunch of thrusters on it and after you make it you press E (or whatever your control is for it) and it will take off. I would recommend putting a gyroscope on it.

First go to flight then place down a hover drive. Press A for options and set the hover height to 128 (end of bar) and the activate control to R and T then place a repulsor drive. Then place a gyroscope and set the activate control to T. Then all you half to do is press T and it will start flying. Use the controls like normal W to move forward s to move back a to move left a n d to move right.