Onto the steps: (Made a typo there.. arrows were supposed to be red.)
I'd highly suggest playing around with the smudge tool until you get some sort of idea of how to use the tool. This tutorial loosely outlines how I smudge.
And no, I won't be making a tutorial of that signature alone. However, I can lend you the PSD.
Then in the layer settings change it to "Linear Dodge (Add)". Or you can just use a different colour altogether.
Settings: hard brush, any size (situational), 72%/90% strength.
Thank you for the share friend
wait for more tuts
Must have taken quite a lot of time making it, right? (Nevertheless, I should make a new one soon, as well. )
There are a lot of smudge tuts on DA but this one is very detailed and shows the reader how to make a smudge step by step, so you did a good job, without doubt. (: