Starting, sticking to it, finishing!

[Forrestimel]

I start out with the background and then do a quick sketch. So far so good. This I can do all day every day.
Problem starts when I actually start applying colors, "defining" shapes and so on. I just loose all interest. Cause it doesn't look like the reference. That's when I start half assing it.

Am I doing something wrong?

What do you do in these situations?
Do you have any issues you want to overcome?

I'd suggest reading up on color theory and light if that's what your downfall is at the moment. And when you are picking colors you really need to focus. Learning color theory will help you notice what colors are what and where to look for colors you wouldn't notice usually. While you learn, do some still life studies, and look for those colors you might not normally notice like reflective light of a nearby object bouncing off of another nearby object. Apply what you learn.

Take your time when you study too, doing a study doesn't all have to take place in one sitting. I've left a study alone for a day and come back to it, sometimes it helps you notice things you wouldn't normally notice (Just like Conny said).

Basically just be careful on what colors you choose, take your time and be patient. Also if you still think something is wrong with the picture then simply flip the image. You'll notice what's wrong almost immediately ha

I hope this helped :)