Best way to merch is to find Items that have hit quite low prices, something that is lower then what its been in along time, stock up like mad, and wait for other people to do the same/clan picks them up.
Currently I have 71k magic amulets, bought for pretty cheap, now its hard to buy for max.
I have 4k muddy keys, bought them while they where still crashing, now its hard to buy max also.
just practice on a small scale at first and then go from there, and NEVER panic, dont sell urself out cos it dropped alittle.