If you can do it, a 20g tall tank is a MUCH better size, especially for what you want to do, and it wil lbea easier to build and care for.
If you DO want to do it in a 10g, here's a pic of my newt palu to give you some ideas:
You can read the thread about it and see more pictures here.
I use a Whisper 10i in this tank. It works really well (in fact, I never change the media or clean it, lol), and it is easy to make a waterfall with it.
I'm tired of this being so small though, so I'm setting up a 20g tall for her soon, since I have an empty one.
Be aware that some newts don't do well in deep water. You should find out exactly which species you are going to house before setting up the tank.
As for fish, newts need cold water, room temp TOPS. That limits the fish you can keep healthy. I have had good results with wild type guppies, they just don't breed or grow quickly in the cold water. Male WT guppies can be QUITE beautiful, and they stay small enough to house 5 or so in my palu (it's important to note that while there are no plants in the water, other than a native moss that seems to like being aquatic, the roots from the terrestrial plants extend below the water line, helping to keep the water "clean", make sure you have enough plants to handle the bioload if you overstock the water portion).
Now, if you DO use a 10g, I suggest doing your land portion as a freestanding "shelf". This will allow you to maximize the amount of land you can provide and also increase the amount of water. This is what I am planning for the 20g for my newt. You can do this with shallow water OR deep water, depending on the needs of the species you choose (might I suggest T. granulosa? Very fun to watch, and such personality! This is the newt that I have, you can see pics of her in the palu if you click the link under the picture). Just let me know if that is interesting to you at all, and I can give you some instructions and direct you to some places to get more info.
Whatever you decide, good luck! Keep us posted!
If you DO want to do it in a 10g, here's a pic of my newt palu to give you some ideas:

You can read the thread about it and see more pictures here.
I use a Whisper 10i in this tank. It works really well (in fact, I never change the media or clean it, lol), and it is easy to make a waterfall with it.
I'm tired of this being so small though, so I'm setting up a 20g tall for her soon, since I have an empty one.
Be aware that some newts don't do well in deep water. You should find out exactly which species you are going to house before setting up the tank.
As for fish, newts need cold water, room temp TOPS. That limits the fish you can keep healthy. I have had good results with wild type guppies, they just don't breed or grow quickly in the cold water. Male WT guppies can be QUITE beautiful, and they stay small enough to house 5 or so in my palu (it's important to note that while there are no plants in the water, other than a native moss that seems to like being aquatic, the roots from the terrestrial plants extend below the water line, helping to keep the water "clean", make sure you have enough plants to handle the bioload if you overstock the water portion).
Now, if you DO use a 10g, I suggest doing your land portion as a freestanding "shelf". This will allow you to maximize the amount of land you can provide and also increase the amount of water. This is what I am planning for the 20g for my newt. You can do this with shallow water OR deep water, depending on the needs of the species you choose (might I suggest T. granulosa? Very fun to watch, and such personality! This is the newt that I have, you can see pics of her in the palu if you click the link under the picture). Just let me know if that is interesting to you at all, and I can give you some instructions and direct you to some places to get more info.
Whatever you decide, good luck! Keep us posted!