Magic rings//rare rings Magic Amulets//Rare amulets have a good chance of rolling with an MF affix.
Boots and gloves also. So any rare gloves, boots you see drop, pick them up and use Cain to identify them. 20+ is a good start for each piece. 100% MF will improve your odds by a lot, after that start seeking known MF items: Ali Baba, Gull, Skullders Ire, you can make Wealth with Lem Ko Tir in a body armor also.