Something that I have found very effective when it comes to getting more player investment in my campaigns is to allow some creative control with some of the characters Items. One of the ways that I do this is by asking all sorts of questions about the items and weapons they are carrying. It does not change the stats of the weapon but will add value to the game as a whole. This video shows you how to do it. I have also created a free PDF that has a simple table you can use.
I also read Viewer questions.
A simple list of questions you can ask your players to get them to think more about their characters and to get them more invested in the campaign.