Hmm. You should just start out with having a sales page here under marketplace like the rest of us. Be aware of upgrades on buyback will change prices as RSI adjust ship prices. Also become familier with paypal fees for transfeering money.
Also most people want a invoice for paying for the ship(s) they buy. This is so in case of fraud from buyer etc. they can claim the money back from paypal.
I recommend to take a look on the ppl selling and what info that are there about the sales. You can learn a bit just from that. There are few people here selling alot of ship and upgrades.
https://www.testsquadron.com/forums/marketplace.71/