Looking back to the countless episodes of the OC, mini skirts were always spotted on Marissa and Summer. The perfect skirt is should be a lower-slung, loose skirt. I think length should never be too short because that's not very attractive. Denim mini skirts are always a good staple to have in your closet but if you want a more up to date look try a sequined one, their fun and you can dress them up and down. I have one in black from Delia*s and I love it. Another up to the minute trend that can be applied to west coast style are plaid shirts. Jean shorts, or the denim mini would be perfect to wear with this type of shirt and perfect for the look.
Since California is on the west coast, that means there are plenty of beaches and warm weather ! The perfect california bathing suit is your classic two peice string bikini. I know that Pac Sun carries super cute bathing suits and their always on sale. The same rule applies with bathing suits as most summer and spring trends. Brighter is better. If your not into string bikini's try a bandeau bikini. I love them and their perfect for tanning because they don't have the straps up to your shoulders. To shield yourself from the sun, grab a pair of ray-bans or aviator glasses and your good to go (;