I decided to build a Knight Titan from House Tarryn for the simple fact that they have fought alongside the Ultramarines in previous battles. For me, themeing my army to the Ultramarines is pretty much the way I go about choosing color schemes and models that are going to be part of my main army.
I used a micron pen to paint the check patterns on the shoulder pad and knee, then Abaddon Black and two layers of Ceramite White and a layer of White Scar to achieve the look I have. It is okay to make mistakes here, especially with the white as black will cover it up pretty well. Deletion is a lot easier than getting it perfect in one go.
This model uses a lot of transfers from the Knight Titan transfer sheet. The hardest part is the tiny ones on the banner. I had to make sure to blot each one as I went to remove any excess water. This is important as the excess water can create the transfers you already have placed to come up and slide around. Which happened to me a couple times while working on this. Getting those transfers back in place can be a huge pain.
Just so people can see the scale comparison, here are my new Knight Titan, Warhound and Reaver. It's pretty impressive to see them all on one board, and I know if I was going to face it, I would cringe - especially after the tournament I just played in.