Here's some options that are available which can help alleviate problems before, during and after prerelease events - some suggestions for players, PTO's and TPCi.
Players: you know you frequent pokebeach. Don't deny it. It may not be everyone's cup of tea, but let's face it, Jon and pals tend to have the premier website for pokemon information. Keep track of upcoming trends, sets, and info regarding exciting new sets, and by all means talk up any of this upcoming exciting stuff with friends.
Have a good relationship with your PTO, and if you think a particular set (or card) will be huge in the format (and therefore might bring larger attendance), let them know well in advance of the prereleases so they can order as much stock as possible.
Be aware that mistakes happen and start times do sometimes get published wrongly. Confirm the address and start times as far in advance as possible. Get a good night's sleep if at all possible, and be washed and use a deodorant since in many cases you may be in a crowd and don't want to be looked down upon for poor hygene. Go to the event early to make sure you get in the registration line well in advance - that way you will be assured entry into the prerelease. If at all possible, bring extra money, just in case you need to contribute for gas expenses, food, or possible side events (which can be really fun!) If you do happen to show up late, make the best of it and enjoy as much of it as you can.
Bring a good attitude - appreciative, warm, and welcoming, not beligerant, contemptable or intolerant. Realize that some people may not know all the cards off by heart, and some (as in both cards and people too) may require a bit of getting used to. Thank both the event staff and also the store or venue owner for allowing the event in that venue. Show that you are looking forward to the next upcoming event, and they will work hard to make your experience just as nice for the next prerelease as well.
Consider doing a theme deck challenge if you are a casual player. It would benefit newer players to have helpful seasoned players as opponents. They may or may not win against these seasoned players, but will always learn something, prompting them to return, boosting growth. You may find that if you are a collector as well that theme decks have some alternate cards you may have never had the chance to acquire otherwise. Believe me, it's a win-win situation and promotes more player participation.
PTO's: be aware of upcoming sets, learning as much as possible about the composition of them from sources (pokebeach, players, hints, and any possible skuttlebutt or gossip available) to influence your prerelease order. If you know your players think a set will be great, a card (or cards) from the set will be somewhat gamebreaking, extremely valuable and hard to get, or that there's a possibility of new and interesting card varients (like this new 'dragon' type), then max out on your order as much as possible - you'll be glad you did. You may not get as many promotional items as you need if you do end up with a large attendance, but sharing what is available from older players who may not care to have the promos, redistributing among the younger groups will encourage sharing, caring and loyal customers.
Again, max out your order as much as possible. Build anticipation by talking about the set and event series long before you even send in an order. Attempt to go past your comfort zone and allow room for side events, getting enough extra product for possible drafts, or even secondary side prerelease events. Many players love to play in a side event to get more product if available, and if you promote it (a side prerelease event, draft, mutant draft, theme deck challenge, or a combination of those) loyal customers will be sure to take advantage of it. IIRC, I think there was even a prerelease that we had a main event and 3 side events! A full day of pokemon for those who can afford to do so makes the event a great success returning many loyal customers. It also tends to eliminate extra stock sitting around gathering dust that you have to pay for.
Try running a theme deck challenge for new players and promote participation by casual seasoned players. You can run this as a side event or at the same time as the main prerelease event. You may find you get a number of people willing to play in that event EVERY prerelease - I did. Many people find it attractive to not have to create a deck, making decisions about content. They just open up their boxes, sleeve the cards if they want, and play. If you find you don't have enough interest to get 8 players in a pod, (here's where foresight comes in handy) and you still have players who are interested in purchasing the theme decks, you can drop 20 cards from their decks and allow them to play in with the other players. If you had the foresight to look over the contents of the theme decks beforehand, you might offer a decklist suitable for the player that you made with only 40 of the available 60 cards. Not only will that speed up your event start time, but it will also cut down on time needed by event staff to oversee any deck changes.
Bring a good customer friendly attitude, welcoming everyone and thanking them for attendance. If you have more than one prerelease, bring as much product and promotional materials as you can or as seems fitting. For example, if you have 2 events, don't leave half of everything at home. If you have 3 events, don't leave 2/3 of the material at home. Larger attendance may surprise you and you might not have enough promotional items to go around. Use common sense as to how much you might possibly use though, not allowing a whole event's worth of product to be used at a previous event.
If time permits, mention any worthy combos you noticed and found interesting in the set. Let people realize you know not everyone will be able to pull off those combos due to the luck of the draw, but pique their interest to see how that turns out.
Do everything possible when it comes to problem solving. Good customer relations are paramount. You want them to keep coming back don't you? If there is a problem discuss with them your solution and see if that may appease. If not, try finding out what they would suggest as a solution. Maybe you can have some common ground. Even when profanity is used against you, a mild answer sometimes can calm things down. Violence and cheating/stealing however should never be tolerated.
Run the main event with as few rounds as you can - dropping the event after as few as 3 rounds (with low attendance), allowing TOM to let you know what the standings are. Let's face it, during a normal prerelease what else is there to gain by playing out all possible rounds? Players won't get any extra boosters, that's for sure! (However let's look at this in another suggestion below.) This will allow you to get to more fun side events where you can offer prizes as you see fit.
Don't be cheap! Consider what you give as compensation to your staff as an investment in loyalty. If staff is well trained and helpful, make it known that you appreciate it, and are willing to compensate them for it. Lackluster compensation breeds lackluster work in the future and poor loyalty.
Speaking of that, it's nice to give out an extra pack or two for those who are new to the game (possibly adding extra promotional items from earlier events as you may have available) so they continue to come back and feel that they get value for their investment. PTO's sometimes don't realize that they aren't the only ones with an investment in pokemon.
And hey, I know this is sorta frowned upon, but now and then it may not do a lot of harm to occasionally drop an extra pack per age group on the winner of an event, if you happen to have a few available - side events especially, since everybody likes to know they are appreciated when they win. Again, don't be cheap! Disclaimer: Don't let TPCi know I told you that!
Thank the players for coming after the event is over, and show genuine interest in them - not just as your customers. If the venue is not yours, be sure to thank the owner personally. Believe it or not, occasionally thanking TPCi for the opportunity to run these events will go a long way towards goodwill in the future as well.
Continue to look for new venues and league locations, not relying on others to do the work for you, assisting them any way possible and where feasible, since this too breeds loyalty and possible new sources of future prerelease venues. If you have only 2 or fewer prereleases currently, bug TPCi to allow you to use these new venues for new prereleases CONSTANTLY! You must have heard the old expression, "the squeeky wheel gets the grease." Sooner or later, when one becomes available, you may be able to acquire another one. And if it's successful, then it may become permanent.
Upload your events as soon as possible, and figure out what you owe as soon as possible. Procrastination doesn't pay.
TPCi: Hmmm long comment, maybe I better give suggestions in another post.
PTOs CANNOT give extra packs to winners of an age group!!!