I love going to the West Side market, it ALWAYS perks me up when I go. My hot spot is the fruit and veggies isles, where I walk up and down the rows at least once, before I begin my rampage. I not only advise you to barter, but I urge you to be steadfast in getting yourself the utmost best deal. If one vendor says they can't do that price move onto the next. There are over 30 stands selling almost the same things, just check the merchandise you are getting before paying.
I think bringing small amounts of cash is always better, that way you can pay stands easily and have fun bartering. I usually go around 3-4pm near the end of the day. I don't like HUGE crowds, which believe me you will encounter here. I also like it because a lot of stands are trying to get rid of their merchandise and will be more apt to give you a better deal. I mean who wants to put everything away back into their truck after a long day of selling?
Bring your appetite because a lot of stands will give you a free sample of the fruit! Be ready for the hustle and bustle but overall it's a great experience. Be ready for the excitement of getting a good deal!