I struggled at a few points during this quest so I figured I'd post a quick reference for anyone who is a warframe noob like me.
Firstly, in order to even start The Sacrifice, the "Personal Quarters" must be built in your foundry. This opens a room in the rear of your ship. Approach the window and interact to play through the intro.
At one point you will be tasked with cracking an Orokin Cipher. Simply find the markings on the walls around you and they will light up. Once you've found them all, return to the cipher and input those symbols. They should be hovering above the cipher at this point directing you which symbol should go into which slot.
A few times throughout the quest you will have to fight/stun Umbra. To do this, transfer out of your frame to your tenno/operator. Use RT to remove his shields. This can take awhile, try running around, using LB, etc to escape and let your RT recharge. Once his shields are down, use the melee attack (B) to stun Umbra. This move is a bit tricky to land, I had more luck in close range. Immediately after stunning Umbra, press RB to use transference into the Umbra warframe.
You will also need to defeat multiple Sentients/Mimics during the questline. The best strategy for me was to use my primary weapon until the enemy became resistant. Then use transference and shoot them with the operator's void beam (RT) to remove/reset their resistance. Then transfer back into the warframe and repeat the process. I tried to utilize cover whenever possible and lure the Sentients/Mimics into 1-on-1 combat whenever possible.
Anyone who plays a decent amount of warframe probably won't have much trouble with this quest, but since there wasn't anything posted here I figured I'd add a few tips. Cheers.