@Sofa @Skua Thank you!Ill try out your tips for my New Years special plane!

My process is as follows:
-"Sketch" out a functional design. What sort of role will this aircraft fill? Place some fuselage pieces and wings to start off, focused on accommodating that role. A fighter would probably be designed for speed and maneuverability, whereas a bomber would likely have to be big and powered by multiple engines.
-Tweak aspects of the design (fuselage length and shape, positioning of wings and control surfaces, etc) and test them in sandbox. Experiment to see what kind of configuration feels the most suitable.
-Put in detaily bits and tweak the appearance, so long as it works the way you want it to. Working from some kind of reference (even if you're not making a replica) often helps. Fiddling with numbers in the .xml files may be necessary to get things the exact shape and size you want.

Try drawing your design out before you start. It's okay if you're terrible at drawing, it's just to help you keep a clear idea of what you want, and it also lets you work out the details before you start

If you haven't already, learn how to use the fuselage block.

maybe try looking at my planes :)