First, look through all the images on FA. The idea is not to "memorize" a particular image, and yes I agree some of them are quite difficult, but there are also some really obvious gimmes. For example, images of things like pneumothorax... or double barrel aorta... or.... india ink with cryptococcus, etc. No matter HOW you get an image of one of those, they will all look the same. Same as things with histology like... Kimmelstein Wilson nodules... or crescentic glomerulonephritis... etc. Some things are so obvious that they look the same no matter what angle you take the shot in.
Other things as long as you practice you should know where things are. Things like brain scans or arteriograms. Do each and every single one look the exact same as the one in FA? No. But you should be able to figure things out if you know where the structures are.
If you can do all of that, you should be in good shape. That doesn't mean that you'll know EVERY image that pops up on the exam, but with the history, you should be able to reason it out. For example, right now I'm doing UW blocks. Have I seen EVERY SINGLE UW IMAGE BEFORE in my previous studies? No. But I can usually figure it out.
Resources I would recommend learning images from (in this priority) are:
--FA
--pathoma or RR for path images + sites like
http://isc.temple.edu/neuroanatomy/lab/atlas/S5/ for selective neuro images
-- Qbank images
