People generally say that larger tanks are better for beginners due to there being "less room for error". I disagree with this statement; I feel as if there is just as much room for error in a large tank as there is a small tank. When they say this, they are generally referring to toxins that build up as by-products from the nitrogen cycle, or minimizing the effects of accidentally overstocking (which again results in toxin buildup). With that being said, before anything, I highly recommend reading about the Nitrogen Cycle, particularly in a closed ecosystem such as an aquarium. I think you should start with a 40 breeder. It is the perfect size, in my opinion. Or, go for a 55 gallon. Starting at one of these sizes will allow you greater freedom in species choice as well as your total fish capacity.
One of the most important things to know is that, while many have done it in the past, simply filling your new tank up with water and plopping in 40 fish really isn't the way to go. I highly recommend reading about fishless cycling as well. What you're doing here is basically getting all of the nitrifying bacteria established (those that take part in nitrogen cycling) so that they can accomodate your new fish down the road, without allowing waste by-products (NH3, NO2, NO3 [not so much]) to cause any harm.
I'm sure this sounds really confusing, but try starting with those two things and go from there.