Cut your shots 50:50 with sterile filtered oil. If you want to use 50mg of Testosterone Propionate, and you have 100mg/mL Testosterone Propionate- pull 0.5mL of your test prop, and 0.5mL of sterile filtered oil to shoot 1mL of 50mg/mL Testosterone Propionate. This is the #1 best way.
Dont bother with b-12, its water based- absorbed so quickly it will have little to no impact.

I didnt know we could do this... Does the raw get suspended properly if we cut it with oil before injection...?

With the pain test-prop gives, heck Id rather shoot 2 ml than deal with the pain that 1 ml shells out.