Need dreading help!

So yeah, this sunday I'll be dreading my girls hair, after which she'll be dreading mine.

Twist n Rip method.
We'll be tidying up with a crochet hook afterwards.
My hair is about 30-40 cm long.
My girls' is about 40-50 cm long.

We've obviously read guides and watched plenty of vids.
Though any tips will help!

 

I'd use the locking gel that http://www.knottyboy.com/ sells.
Goodluck, I have always wanted a nice set of dreads!

 

Not using any kind of wax, she's against it with good reason.

 

Ive only ever seen it done with wax to be honest!