I use a mix of encounters of my own design, and encounters taken from published modules (though I will often tweak these in various ways - adding or subtracing monsters, changing maps, combining multiple encounters into one, etc).
For scenario ideas I will sometimes be inspired by published modules but always link them into an overarching scenario or story framework that is my own. I tend to find that many published modules have interesting premises or suggest interesting antagonists, but don't do an especially good job of developing this into something that will engage my players. So I'll take the premise or the character and work it into my own campaign.
For scenario ideas I will sometimes be inspired by published modules but always link them into an overarching scenario or story framework that is my own. I tend to find that many published modules have interesting premises or suggest interesting antagonists, but don't do an especially good job of developing this into something that will engage my players. So I'll take the premise or the character and work it into my own campaign.