1. Since this is just a rough work, I will be a more general on the critique.
2. Height... Booker looks far too tall to Elizabeth. By the canon info wiki...
~ a. Booker DeWitt's height is 6 feet, 1 inch (1.85 meters).
~ b. Elizabeth's height is 5 feet, 6 inches (1.68 meters).
3. Width... Booker is very physically fit, yes; however, he is not as bulky as depicted here. Think more "martial artist" fit rather than "(American) football linebacker" fit.
4. "Anna DeWitt"... Do not forget that Booker covers up the "A.D." tattoo with bandage wrapping after he realizes he is (literally) marked for death by the Columbia residents from Comstock.
5. Bird..? or the Cage..? I look forward to seeing which you will choose & depict.