Older Players vs. Younger Players
Older Players:
Have more money, so selling more expensive items in auction or trades should be
done when they are on. This could be letting your expensive auctions
expire during the later hours of the day, even if you play in the early hours.
Younger Players:
They will bid on overpriced things at auction, so put your overpriced, cheap items up during the times that they are on. Also, they are more gullible to buying your hard to sell items, or what not. Remember, their ignorance is your financial gain.
They are also willing to take less or give more in the trading post, so when a lot of kids are on, keep that in mind. Also on the trading post, they tend to prefer "stuff", more than points. If you have cheap, but interesting looking stuff, my friend says that sometimes they will take it.
Also, younger players are much more prevalent on the weekends.