Well, while I can't see the picture, (stupid school filters!) I would wait until spring before messing with the tree- you don't want to get it down to what you like and then suffer winter dieback! Leave the foliage as is and repot it once it has enough leaves to support itself in the spring, and then leave it alone. The tree will probably stop growing its canopy and focus on its roots. Once you've gone through a period of relative non-growth, and then the tree starts growing its top again, you can prune the branches. This may happen in late summer/early fall or not until next spring. If it starts regrowing in late fall, don't mess with it- fall dormancy preparations are very important and should not be disturbed. All of your styling will be for naught if your tree dies!
As for styling, generally you follow what the tree does in nature, so a good broom, informal/formal upright, or windswept are all good choices.
Good luck! Oaks are very hardy and easy to care for once you've got it styled, but it is a slooooow grower and doesn't recover as quickly as other plants.