From what I heard it is beneficial.It can be done before a ritual to relax as it is scientifically proven that after climax you relax naturally.
It also can be used in sex magick as High Priestess Pythia used it to free Demons.Generally you can use it for sex magick.She said so on her audio sermons which you can find on YouTube
Here is a nice page I came across, I liked it very much as it is clearly written http://sexuality.about.com/od/masturbat ... ion_fx.htm
Masturbation is not wrong. It won't make you blind nor will it make your hands hairy.
If you're feeling this you need lots of self-love. Take a read of the PDF on this link:
Here is the link to Self-Love Masturbation/Tantra PDF. https://www.google.co.uk/webhp?sourceid ... tion%20pdf
No it's not bad its normal and healthy
Keep calm and hail Satan.