My Girlfriend always says she wants me to be more dominant and not be a wimp about it. I guess she thinks I am too nice in the bedroom. She likes to behave like a brat and wants to be punished. I can do the spanking, dirty talk and preventing her from cumming but I just run out of ideas on what else I could do.
Any tips or suggestions would be appreciated.
Blindfold her and gentle restraints to start off with? I used to love being treated kindly, & now like a bit of dominance. I’m guessing she really trusts you & feels extremely comfortable with you to request this. Good luck x
Try some mild bondage or restraint.
Under mattress restraints are good. We also use wrist-to-thigh restraints and/or thigh spreaders. Couple any of these with a blindfold.
Nipple clamps can be fun too.
Hi there @Eva12 and welcome to the forum. Unfortunately your first post has broken the forum rules. This is Lovehoney’s forum, so links to competitors’ websites aren’t allowed. 
Restraints and sensation play are good places to explore. Taking away certain senses as well, like by using a blind fold or noise cancelling headphones. You could try out forced orgasms to counterbalance your orgasm denial. It could be worth filling out a kink list to see what you’re both in to.
Hmm maybe try watching some videos on dominating to get fresh ideas 
Maybe talk in a little more detail with the GF about it in terms of expectations of when she’s a brat?
There are so many variations of dominating, and although it is nice to be given the level of trust and a blank sheet to work from.
If she likes being spanked, can take that further with paddles, whips, canes, and restraints.
Tell her what you expect from her, and issue ultimatums. If she doesn’t like the punishment, she’ll comply with your demands maybe.
My biggest fear with ‘blank page’ approach is where my OH’s boundaries are and worrying about crossing that line. So if you are going down the experimentation route, would strongly suggest a safe word - that way there is no confusion if either of you need time out.
As mentioned in comments above, there are lots of avenues like videos where you can get more ideas from, but I would suggest your golden source of info is your girlfriend herself. She may want to leave it in your hands, but if she gave a specific example of what she wants then you can find out a lot more (whether it is being told what to do, humiliation, pain, teasing, restraints, forced acts etc.,).
@Mr_Kink1 has covered it all really.
She probably has done some research and knows what it is she wants so ask her.
Draw up a list of rules and punishments/funishments. Establish a safe word for the bedroom and outside of sexy times. Negotiate and communicate.
It will take time to get a happy medium for you both.
I love impact and restraint in the bedroom along with lots of edging but have little tendencies after a scene and need lots if care and attention. In everyday life I love a certain amount of service on both sides and can be very bratty.
My husband/Sir has alot to deal with but we are still always talking and adjusting if sometimes something isn’t quite right or has changed.
Thank you for all the suggestions. Essentially I have been given a blank slate. I have talked to her asking what she would want and it’s always ended up in her saying that it’s up to me. Not sure she knows herself which is why it’s in my hands to find out what her limits are. We also already have a safe word if I go too far but she has never used it yet.
I do blindfold her tie her up but will invest in some nipple clamps suggested by @rockstar and a paddle as suggested by @Mr_Kink1
I will also have a look for some videos @AJSTAR for inspiration 
Exciting times! Keep us updated on how it all goes