Hmm... Looks pretty good. You have a few things to consider, though.
First, dwarf gouramis will kill eachother. Get only one. Even if the pet store tells you they're peaceful and will get along, they won't...
Second, you need several otos. They aren't schooling fish, but they prefer groups. I'd say get about four, and make sure to give them algae wafers when they run a bit low on algae.
Third, I'd suggest you add about three more black neons... They'll enjoy a few more friends.
Is the tank planted?