Lens flare isn't a good way to create lighting. Instead of using it do the following:

Black layer
set it to linear dodge
Get out a 100 px paint brush, o % hardness and 80% opacity. brush once in the color of your liking where the lihtsource should be.
Finally if you want to go a step further you can duplicate that layer and gaussian blur it to add color to the sig and give the lighting a really glowy effect.

I think you need to work on your blending. I can see the guitarist very easily and he seems to be very pasted on. WOrk on c4d's and clipping mask and smudging to get him blended easier.