I was pretty involved in bench research during pharmacy school, through cold-calling, but in retrospect, clinical research would've been more useful in getting into residency (I loved bench research though and thought clinical research was boring). For residency, I would say that that things like GPA/grades (especially in therapeutics courses), performance during clinical rotations, and letters of recommendation are more important. If you're going to do research on top of maintaining grades and everything else, I would focus on clinical research, which would mean cold-calling clinical pharmacists/professors. Clinical research is definitely preferred over bench work in the pharmacy world, especially since it's clinical research that residents end up doing. Actually, a lot of clinical pharmacists that I've encountered, don't really care about bench research and feel like that experience is irrelevant. An easy goal would be to present poster at ASHP MidYear or any other pharmacy conference. I think that would make you look like better candidate for residency. Personally, I ended up working on research during school breaks and during my final rotation year, because classes took up all my time during the school year.