hmm, I can think of a few different ways to go, depends on your goals & resources.
Thoughts
a 10 gal is high maintenance just becuase of size, even things that could do in a ten, require more cleaning and care than if the same animal were housed in a 20L
first ? lifespan - do you want to (also can you) invest in and try to keep a long lived animal
feeding options, what kind of feeders will mom let you keep in the house? do you have the menas to purchase or breed live feeders? ie crickets fruit flies, roaches whatever?
How many years before you will need to move (college, family moving, etc?)
Idea, if mom let you have a newt before, why didn't it work out? If that choice is pre-mom-approved, can the set-up animal species be tweaked to make it work? Always a good idea to stay in mom's good graces. lol