Thanks Donavannj ;) not that it's secret info, I'd love it if everyone took my word as dogma like that!
So for the sets. First, I'd recommend selling them as seperate sets just because you'll be more likely to sell that way. There isn't really a market for buying several complete sets at once, someone who is that serious about collecting most likely already has some completed sets and doesn't want a lot of excess. Not to mention the fact that no one wants to spend that much money at once, lol.
Pretty much what Pikachufan said and what I said earlier, the Base set is always worth more than any of the others of the original sets, and 1st edition is worth more than unlimited.
Base: $300-600 (price fluctuates greatly)
Fossil: $100
Jungle: $100
Rocket: $150
Gym Challenge: $200-250
Gym Heroes: $200-250
Cards within each set are what cause the differences in price; charizard, blastoise, mewtwo, alakazam etc. are what make Base more expensive (plus the fact that it is the "original" set) and sets like Gym Challenge and Heroes have cards like Blaine's charizard and moltres to increase the set value. They are also just larger sets and include more cards.
My last suggestion is to sell on ebay, it's safest for all parties involved and basically guarantees neither seller or buyer will get ripped off. Hope it helps!