When selling Crypto Currency, don't sell in haste, check the prices, sometimes a day or two either way can increase your profit greatly.
Never sell with Paypal as a payment method, they don't like any digital products and services, so will always side with the scammers. Pretty much the same goes for eBay, quite obvious since they are both owned by the same people.
Depending on where you sell, try to protect yourself as best as possible, so ask for ID.
The simplest solution is to sell on an Exchange or trading platform.
Coinbase, the most well know and easiest way to buy and sell the main Cryptocurrencies. They even have an app you can use. Also they give you a bonus when you trade $100 / £7.
LocalBitcoin – They act as an Escrow agent
Bitfinex (proper exchange & trading platform)