Biting your nails- it's a habit I have and many other people have too.
I'm going to write a blog on how to stop biting your nails painlessly and easily... :)
1) Paint your nails with a bright colour- so if you start biting then you realise.
2) Push your cuticles back time to time as they are growing.
3) Find something else to do- for example, chewing gum.
4) Imagine your new lovely nails.
Or you can just cover your fingers with plasters- this will stop you completely from biting them because the plaster will get in the way (this is the solution if it gets very bad).
After all of this, you can purchase many nail kits that sort out your nails, for example:
http://www.boots.com/en/Leighton-Denny-Totally-Groomed-The-Essential-Nail-Kit_1051244/
What I see many people doing is giving up and just buying fake nails and gluing them on. If you know how to do this or get it professionally done it is much better. The glue is very hard to put on and if it gets stuck around your nails, not only it makes them look very unattractive, it also damages your skin. And it can hurt a lot if your fake nail falls off. Personally I would recommend to first try growing them and only if you feel you have to then use fake nails.
When I tried to not bite my nails I used this nail varnish:
http://www.boots.com/en/Mavala-Stop-Nail-Biting-Treatment-_1037856/
It's especially designed to put you off biting your nails- it gives your nails a slight shine and every time you go to bite your nails it tastes horrible. Putting you off biting those nails- VIOLA!