Paul Farquhar
Legend
Ideally, you set this up in session zero. I've run campaigns with both heroic and criminal PCs. But you need to make sure the DM and the PCs are on the same page from the start. I could easily see "lets rob the store" leading to PvP combat with a more law abiding player character. Have you considered how you are going to deal with that?Telling the players how to play (as per your above "I want you guys to do (semi-)heroic things" example) is in my view just as bad as the other forms of railroading we've seen posited here.
Of course, knowing to do this stuff comes with experience. And I guess having reasonable expectations for what a DM is able to do does too.