Most of the folks on here have a lot more experience than I do, but in the bit of trading I've done, I'd say don't neglect building relationships - with local comic stores, other collectors, estate sale folks, etc. Almost all of the books I've gotten that were great deals, unique opportunities, or cool collections were because I knew someone. It was the comic store owner who I constantly chatted GA with who had a collection walk in the door, or a friendly neighbor I'd known for years who one day heard me talk about collecting. Or it was the estate sale manager who already had a friend who got first dibs on collections. With the comic shop, I wasn't looking to get keys, but I was always talking to the owner about his wall books and bringing in new finds I picked up. So when he got collections or was in talks with a seller, he would let me know first. This is just my humble opinion being very small-time and very new, but in my experience, those relationships built around the hobby have been really valuable - financially and otherwise.