DIY high/lowlights!

[Nonky]

Hello
At the moment I have shoulder length medium brown (dyed to cover the grey) hair. I would really like some more 'oomph' as I am feeling tired and frumpy. I am on a really really tight budget at the moment but I would like to look a but more glam! (I have a looooong way to go)

Is there anyway I can do my own highlights? Does anyone know of a good hair dye that will give me less of a 'blanket' colour with a bit of colour difference?

Thanks in advance :-)