There are so many options learning radiology. I used a combination of traditional textbooks, ebooks, websites, and journal articles. Ultimately, some thoughtful self-reflection is needed to determine the best strategy that works for you.
Check with your institution to see what library subscriptions they have, and what books you can access for free. For example, mine has a subscription to Clinical Key, which allows me to access all of Elsevier's textbook library for free (including PDF downloads of individual chapters, which are nice for reading on a large tablet screen).
Should I start a large question-bank (like RADPrimer) right away? I think this is a mistake. There is plenty of time to do questions during your third year for board preparation. Years 1-2 is the time to read textbooks, journal articles, review teaching cases, and perhaps some quality, in-depth questions with a stronger emphasis on education.
Learning how to quickly find, evaluate, and apply information from internet resources such as Radiopaedia, online journals, and websites is a important and complex skill itself. While it might be tempting to "skip over" the hard work of in-depth study and understanding in favor of leaning on these expansive resources, there are no short-cuts!
Read 1 core textbook for each rotation during your first two years of residency; this way, you will always have a core, comprehensive resource that you know well.
As you come across interesting cases during the day on service, do a focused literature search and read articles to learn more about that diagnosis. Do this as often as you can. If you are really busy on service, then write down a topic that you will look up that night so you don't forget. This sort of knowledge will never leave you.
Collect interesting cases during your training in a HIPAA-compliant way. My PACS (McKesson) allows me to do this with Study Share. Although seemingly small, the simple act of saving a case helps to permanently embed that case in your memory. Sharing them with your colleagues during down time on a service or interesting case conferences will only further reinforce them. I am astonished at how many saved cases I can almost "see" in my memory.
Share your growing knowledge with the world: Contribute high-quality cases to Radiopaedia to advance radiology education throughout the world.
Follow-up your cases!!!
If your interpretation sends a patient to the OR, read the operative note!
If you recommend a biopsy, read the pathology report!
If you are unsure about what the diagnosis is and give a broad differential, follow the patient's hospital course!
Doing these things will give you a profoundly sophisticated, three-dimensional understanding of what it means to be a radiologist and take care of patients.