I think a good example of how to do this sort of thing right is the "Hey Ash Watcha Playin'" videos on YouTube. They make content about games. Sometimes they're paid to make content about a particular game, and when they do they write "(SPONSORED)" right in the title of the video. Still good content, I could avoid clicking on it easily, but I watch it anyway because I like the channel and know it'll probably be funny anyway.

A bad example would probably be that one Kardashian guy who accidentally posted the instructions about how to pose and what to say instead of following the instructions.