Honestly, go as big as humanly possible, or as large as space and budget will allow... i remember when i started with my 25G and thought sweet, then jumped to a 60G and thought okay this should last a little while, then the 200G, all this happened within a matter of about 3 years, and now i already want a larger tank around the 400G range, although i just don't have the space for it unless i get rid of my 200G which i'm not going to do any time soon...