While the Preview is listed to start at 9am, it generally takes about 2-3 hrs for everyone that is attending to go through the lines, some going through multiple times, paying and hoping to get the "hot" card(s) everyone is dying to trade for. Mini-tournaments usually start up around noon- mostly sealed packs and last for about another hour. Rules for the preview:
1. If you're bring trades, keep them in a binder and in a zippered bag or pack that you can carry at ALL TIMES!!!
2. Do not attempt trades with more than one person at a time. If they are looking through your binder, wait until they finish before looking at their trades. This enables you to watch your cards WITHOUT being distracted. Distraction is what most thieves look to do before stealing your cards. Stand firm on dealing with one person at a time. Believe me- if you have what someone is looking for- they're not going anywhere!
3. Know the value of the cards in the preview in advance if possible. Look for sites that have the spoiler information prior to the release so you know which cards to keep, which to trade and if trading, what is the value of the card traded. A lot of people will be looking to rip kids off thinking they don't know they have a card worth more than they're willing to trade with. Had someone offer me $5 for Magical Stone Excavation when I pulled it from a Champion Pack when it first came out.
4. Have fun. Have fun. Have fun. Duel others for the fun of dueling. It's a great way to meet new people and build up your skill level while doing it.