Hi Jayda and welcome to RetouchPro,
One easy way to get an image with a better contrast between the hair and background would be to duplicate the layer, set blend mode to exclusion and it gives you the first image I attached, This should allow you to create a mask a little easier. Along the same lines you could duplicate and screen blend a couple of times and get a decent contrasted image to work from (attachment 2)
Will that help?
There's also a pretty good thread
here dealing with hair selection