you have got the right idea, dont jump into this..... research and find what suits you best. and buy the best you can. if not your gonna end up upgrading down the road. this hobby is very very addicting.
as for tank size yes as stated above bigger is better. if you go tooo small you will end up regretting it or just getting a bigger tank (I know I have upgraded 3 times in the past 2 years, I am in the process of setting up a 400 gallon right now)
But as everyone will say on here..........just take your time and dont be afraid to ask for help.