All the useful Restart Checkpoints (RCs) that you need to know about in UC3 can be found in this playlist. This playlist covers all categories and all the combat sections in these videos are how I have gone about them in my All Treasures runs. I highly recommend watching people's runs for different categories to view the context in which these RCs are used.

https://www.youtube.com/playlist?list=PLtxomYWJ-7e6XjKQ3da1i2GSaWdFcAHWh