Some thoughts on preparing for Folsom:

Many years it is very hot, with several cases of heat stroke and nearly universal sunburn. Wear sunscreen and hat, and bring lots of water, or plan to wait in long lines for beverages. One year in ten might have some rain. Check the forecast.

You'll be standing all day on hot asphalt. Very little seating is available, except in the Janus members-only booth. Expect your feet to safeword.

Scening is permitted and fairly common. Several booths provide charity scenes, and vendors allow trying their wares. I've done a raw, intense street scene with cops watching, without a problem. During a scene: avoid blocking traffic (we were on a side street), make sure it looks consensual, and don't endanger passersby.

Various degrees of nudity are common.

Expect a very wide range of sexualities, orientations, and fetishes.

The crowd is 300,000+, so it's hard to meet up with people, and slow to get anywhere. Make some arrangement how to rejoin your group if you get separated. Ninth and Folsom is the mid-point, but still much too big. Specify e.g. "the north-east corner, at the curb". Also, it takes a long time to walk one block during the fair; allocate 40-60 minutes to go end-to-end.

Parking is challenging, less so before 11 am and after 4:30. Driving is very slow near the fair. Plan to walk some distance. Public transit is crowded too.

Early in the day is usually better, since there are fewer tourists, smaller crowds, and less heat. The last hour can be nice too, although everyone is tired, and many are drunk.

If you're thinking of patronizing the bootblack station, by a ticket early. Normally they honor the lowest ticket number first. So if you come back later in the day, you're probably next in line.

Closing time (6 pm) is taken very seriously. A vendor who sells after 6 can be banned from future years. If you're still choosing color, buy the thing at 5:58, then decide which one to take afterward. I.e. no money changes hands after 6pm, or the vendor is banned. Some booths are required to close earlier, due to their location. The police start enforcing vanilla laws at 6, so stop scening and cover up. Also, the city street sweepers and homeless scavengers descend, so leave the area unless you're helping dismantle a booth. Sober volunteer labor always welcome.

FSF now attracts lots of non-players, as well as thousands of players of all types and orientations. Many of the tourists are genuinely curious, but some are just gawkers.

There are lots of cameras, both still and motion, at FSF. Many people will ask permission before photographing, some will not. Almost everyone ends up in the background of somebody's happy snaps, and some of these are posted on the web, or even in "girls gone wild" commercial videos. Therefore, some people alter their appearance, to give plausible deniability: "Gosh, that photo does look a bit like me." Typical alterations include sunglasses, hats, wigs, face paint, and face bondage (e.g. pony bridles). The amount of camera attention you get depends on the outrageousness of your look. Among a quarter million exhibitionists, it's not hard to fade into the background if you wish.

Portable toilets are provided on side streets, but usually have a long line. Some guys go in two at a time.

Bring money or credit cards; there's a lot of interesting toys and clothes. Most vendors are either crafters/manufacturers or storefronts (web and/or brick retailers). The booths of storefronts typically sell the same stuff at the same prices as usual. The makers often sell a broader range of things, for about 2/3 of retail, and they often pay the sales tax themselves. If haggling is your fetish, try it the last hour with vendors who have a long trip home.

If you see something you like, and consider leaving it while comparison shopping, make sure it's not the last one. Things often sell out at FSF. And if you've never seen it before, don't expect to find it on the web later - carpe diem.

If you might be shopping, bring a sturdy bag, e.g. a zippable backpack. Smaller booths don't have bags, and plastic bags don't stand up to the jostling crowd.

Some of the side streets do have booths on them. This can provide a welcome respite from the crowds.

Some club booths are for members only, e.g. Janus and sometimes Odyssey/Fringe have a shaded seating area for members. They also have an information table and a charity scene space.

This is not a good time to start a new diet or make other lifestyle changes. Fainting is rarely erotic. You'll have enough surprises and stresses without messing with your body chemistry and habits.

Some people get overwhelmed with the shopping options, and end up with disused items at the back of their closet. One rule of thumb is "What specific scenes will I use this in, over the next 12 months." When in doubt, ask someone else's opinion.

If you have a large or delicate costume or rig, e.g. a pony cart, parade it very early (done by noon), or only on a side street.

Folsom Street Fair will top you. Relax and enjoy the ride.