It would depend on whether it was pimples which are caused by blocked pores or shaving bumps which are caused by ingrown hairs. If the former, make sure that whatever product you use is non-comedogenic. This means that it will not clog your pores. Also an astringent might be good at helping to clear those up. Salicylic acid containing products generally help clear up acne and blackheads real quick. I use just a bit of it on trouble spots. It burns for a second, but really helps reduce redness and clear thing up in a day or so.
If it is shaving bumps caused by ingrown hairs (medical term is pseudofoliculitis barbae) there are a number of products to use as preshave and aftershave conditioners that help to prevent or treat those. Shave Secret is under $4 at Walmart and claims to prevent nicks, razor burn and ingrown hairs.
Others here might have some better alternatives.