Using reference is cheating
Absolutely not. You will learn to draw with fewer references, but before that, you need something to look at. It's the tiny details that always make it worthwile; how the sinews on the neck strain, what colour a spider in sunset is, how the wheels of an amphibian vehicle are arranged. Every artist learns to draw from models. Whether you attend life drawing classes or use fashion catalogues, you will not be able to get everything right without looking. Besides, all great masters used reference: and if Leonardo drew the Mona Lisa from a model, why would it be cheating for you?
Try this: Before starting the artwork, look at all the inspirational material you gathered. Do a few studies on them. Then banish all of it and, with you head filled with the fresh visions, start working.
I have to stick to my reference
Sometimes you just need the leg pose, or the skirt, or the bomb's shell, not the rest. Piece together what you need for your artwork, rearrange and leave out. If your model has a square chin and you need pointy, go ahead and change it. But be careful; change the head posture and take care of the neck, too; change the vehicle's armour and make sure it doesn't keel over.
If my drawing looks like the reference, it's correct
Sadly, only because your drawing is exact, it is not automatically correct. As a rule of thumb, if it looks wrong, it is wrong. We accept things in photographs because we know they're made from life; in art created from imagination, we expect more perfection. For example: People could claim a portrait doesn't look right because, although drawn from life, the person had unusual or unattractive features.
Also think of this: Many times you will need to exaggerate to make your point clear to the viewer. If something should be slender, make it really thin; if something is supposed to be pointy, make it razor-sharp. Adjust the level of this caricature to your needs.
Anything is good reference
A reference for a painting with strong side lighting will be difficult to do based on a softly lit photograph. A strong fish-eye effect in your reference can be trouble for correct perspective. You will often need lots of refs for an artwork; for lighting, the face's angle, the anatomy, the movement, the background, and several small details.