Up Throw doesn't combo into anything. None of his throws do. I don't really recommend it for too much early percentage use except for mix-ups and juggling certain characters that hate to be in the air. You don't want to stale it either. Save it for kills. I have an up throw kill chart that's listed in the directory if you wanted to see what ranges characters die at on FD. I'm currently trying to expand that to account for rage and other stages.
For neutral air, it has great uses off stage as a gimping tool that can either send certain characters too far to recover, or it can stage spike them. If characters are air dodge happy, you can use n-air to catch them and potentially get them in a combo if you correctly predict where the opponent will go.
And speaking of that...
http://smashboards.com/threads/nair-knockback-guide.413975/
This is a guide that goes into detail about how n-air works and how you can predict the direction opponents get knocked away. This can allow you to set up for either a back or forward air.
Neutral air also has utility as a combo tool, and this is something I'm trying to optimize more myself. If fast falled, n-air now has little enough landing lag where you can follow up with a grab or down tilt. The initial hitbox also can combo into an up smash if you hit with just one hit as well. It's a potentially dangerous but advanced tool that I hope to master more in the future. In the meantime, that guide is very helpful for n-air.
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