I don’t know if I would call this a trick but it is a tried and proven method.
Go to a new forum. Make some outrageous statements that are hard to believe but are true. Challenge the most respected members. PM a couple of these same members with deals just to get there reaction. Get into one or two pi**ing contests. Go into a cooling off period and assess the situation to see if the forum has anything valuable to offer.
Some day I might try it.