its nice to see start using PS , however your sig kinda looks good since you don't havemuch experience with it yet.
now about your siggy , don't make your sigs 2 dark or 2 light .. balance it .. always try to use HQ renders and if you have problems with BG just use a srock BG and add your render 2 it. use a light source using white soft brush 70% opacity and mess around with adjustments settings like photo filter , curve , brightness and contract .. check them all xD
use Filters - Render - Light effects .. and try to keep it on default just pick where you wants the light to come from ..
thats all ^^