I know most of you will already know this so this is for the ultimate noobs.

If you have a render on a coloured background, e.g:


Rather than using the ordinary lasso tool and taking along time just to mess it up,
Right click the lasso tool and select magnetic lasso tool, click once anywhere around the image, carefully go around the image not clicking untill you meet up where you started, look for a small circle under the cursor, click once again.
Open up a new photoshop file with the size you want, do whatever you want to do that, get back on the render's window, select the move tool, drag the render into your Signature and your done. A render in a signature.

This is my first tutorial so please dont kill me for anything ive done wrong
I know i should get pics but i dont know how to get pics of the windows etc. on here

Final result:


I did it extremely fast and took part of his foot and helmet off lol
Just make sure you look what your lasso'ing