You just have to wait for that one time in a gazillion when the 50/50s (and 75/25s) all chose to go your way., Then you might win the MTT.
It is pretty unlikely you are going to be able to blind steal your way to a big stack in a freeroll since everyone is so fearless. You just need to try and play well and get in with the best of it whilst trying to avoid bigger stacks than you.
If you get a 75/25 against a big stack then go for it, you have to make chips somewhere. If you get a 50/50 then probably dont.