Haha! That's the exciting part! You can envision what your future tank is going to look like! 30G rimless cubes are really popular as frag tanks but I don't like how it's neither a nano or a big tank really. It's kinda awkwardly in the middle! If you have the option to go bigger, I would recommend so! + a lot of the cooler fish you need 40+ gallons . As for aquascaping, after picking out your tank size, look at other people's builds. There's this really cool read on r2r that talks about what a good aquascape is. http://www.reef2reef.com/threads/tips-and-tricks-on-creating-amazing-aquascapes.97209/. As for everything else, just takes a lot of reading and research!