You can actually buy a cutting in tool. It is a square plastic thing with a handle on the back and roller type material on the front. You just run this along the edges of the walls as explained above to 'cut in'. This might mean that you don't have to worry about taping the cornices and skirts. You should be able to buy one where ever you get your paint and I don't think they're all that expensive. No more so than a good cutting in brush would be (need to have long bristles and be of good quality).

Good luck!! Once you get started it won't be that hard. I painted a room a few years ago and it came out alright even though I'd never done it before.