Agree with Bowtie: For X-ray, Felson's Book is required reading. Most important thing you will need if you turn out to do clinical work is learn how to interpret where lines are on CXR. Learning radiology is also a great resource, especially their presentations on can't miss diagnoses.
Also, read the FULL report and correlate with the images. You would be surprised how much work goes into looking at a study and how much we see and decide doesn't belong in the impression (for the most part).
As you get more comfortable, especially with CXR, start looking independently at them and compare with the final read. If you disagree, ask your upper level. If you both disagree with the interpretation, call up the radiology resident and ask. We're busy and look at a ton of things, and we realize that 2 (or 3) sets of eyes are better than 1.
As you learn to read imaging, remember that you should always keep the same search pattern. Don't just look and see what hits you in the face. Approach it in a systematic way. A lot of people learn CXR with ABCDE, others work from center to outside. The most important thing is to always look at all the pieces.