Just do UWorld.. that's all you really need. If something's not clear, go to whatever resources you used for step 2CK. It is VERY similar to step 2CK, main difference is ccs parts and for that just use UWorld and the examples provided by USMLE. You just need to make a decision algorithm that works for you... when to send home, when to refer, when to take to ER, when to admit to ICU etc.
My biggest recommendation is take it before starting intern year! Studying right now is painful but look at it this way: you get some distraction from just waiting around for match day and you won't have to deal with trying to study OBGYN while trying to survive intern year. All of my IMG friends that have taken it during intern year say the same thing: just get it done before July 1st and forget about USMLE forever hahaha. Of course you have to study but I felt it was a very different experience compared to step 1 or 2CK because everybody just wants to cross if off their to-do list so the curve is very chill compared to the others. As a point of reference, I scored about 30pts below my CK score and that was still around 75th percentile