Hi hi hi!!
Souljah and Kyle did a wonderful job with this question (on another thread--I think it's called UCSF--is research necessary). UCSF as an institution is very research oriented, but as a medical school, is very clinically oriented so your desire to focus on clinical experiences is well-warrented in that respect. My classmates in ggneral were big clinical and international experiences buffs (I think most people are going abroad this summer in fact!), but the research program here is always trying to seduce us to join them!
Aside from that little tidbit, developing a strong sense of "self" is most important. As Souljah said, decent MCATs, decent grades, strong letters, intriguing personal statements are critical... that will get you by many cuts off and grant you an interview in most cases.. but what makes you stand out to the admissions committee is "who you really are." In a way, focusing all your efforts on research might make you seem run of the mill... especially if you're not passionate about it... Now people really pick up on how excited you get on things. I did a lot of research, personally, because I really enjoyed it, and one of my interviewers told me she'd never seem anyone so so excited by T-cells--and even tho she thought T-cells were a drag, I got her truly interested. That made my day!
Always participate in things that you love, even if they don't seem "med school oriented." There are a feq things people ook for like some volunteer work and clinical work, but if you love ice-skating, submerse yourself in it!!
UCSF is such a diverse place. They pick people to fit every niche. Develop yours!!
Best of luck,
Bien