Selling Cards - Best Shipping Practices?

[Danderlion]

Hello everyone, I am not new to the hobby, but I have never sold any of my cards before.

As of now, I have some lots (complete sets, teams, players) and some higher end individual cards that I would like to sell.

Any advice on the best way to package my card(s) for shipping that will keep them safe in transit and also keep my costs down? (sorry if this is the wrong place for this type thread)

Also, how would you guys feel about buying cards from somebody with very little feedback on ebay?