I am guessing that most of your cards will be fairly recent or from the dreaded "Junk Wax" years (aprox mid1980s to mid or late 1990s). Those years aprox. from 1983 to about 1997 (give or take a year or two) are nicknamed the "Junk" years because there were dozens upon dozens of card companies making at least a dozen different sets each by the 10s and 100s of thousands not just by a few thousand as previous years (Although exact production counts have never been officially relased for any years). This resulted in thousands of cards of just one individual player across a few hundred differnet sets. In previous years there were only a handful of companies making less than a dozen sets each, usually just 2 or 3 and not as many copies of each individual card. Now-days the problem is almost the same but sort of reversed. Instead of a megaton of the same cards being produced they make limited amounts of just a few cards, and tons of sublte variations to those few cards. Cards from the junk years are worth on average only a few cents or less. It is best to sort them by brands and years and sell in large lots. /overproduction years rant.
First find out and be familiar with what you have. It will probably be easiest to sort by sets and years at first because similar looking cards are eaiser to identify. Do some reasearch on the cards you do have and on how much sets from those years are selling for and what the Key cards to look for are. If you have any of the desired key cards those can usually be sold separately fairly easily, the rest should be sold in lots either by set or by team.
