In general, it would be best to take a pic of the item you have for sale, with your screen name written on a piece of paper with todays date on it. (Assuming you have the item in hand)
Next, set your asking price, crypto payment of choice, make sure to include any special details if necessary.
Specify shipping costs, time frame, and who pays for what.
I would highly suggest to offer to use a trusted forum escrow, this will eliminate a lot of scam accusations on your part, and a buyer will feel safer using a trusted forum escrow for any deals.
I can personally recommend minerjones to act as escrow from many successful deals and trades done.
Dent has been mentioned a few times, but I think Qlink will be the bigger winner. They are working on a decentralized mobile network and wi-fi sharing service, not just a data marketplace.
Tron is a shit project. Anyone still holding tron at this point isn't paying attention. Sometimes you just have to cut your losses and move on. It's going to keep dropping.
I think it's going to be a big year for NEO. I'm not holding any yet, but currently looking at NEO and plan on investing. BaaS coins are going to be a safe place to hold if/when the market crashes.
Transaction fees have been somewhere around $20 lately, pretty useless for any kind of micro-transaction. It doesn't matter if vendors like Amazon want to accept bitcoin if the network can't scale to meet the demand.
My money's on XLM. I see it becoming the bridge between cryptos and fiat within the next year or two. BTC is becoming a dinosaur. I'm sure it will be around for a long time still, but I don't think it will sustain it's utility in the future.