In terms of debate, the following have always been the most helpful to me in ensuring that I'm not believing things only because I want them to be true. I've ordered them from easiest to hardest to implement.

In discussions, presume the kinds of conditions that are the least convenient for your argument.

Even if you've been fairly mind-killed, it's pretty easy to notice when someone else raises a difficulty you haven't thought of.

Encourage "Why do I think that" monologues. You elaborate on a thing you currently believe to be true by specifying the reasons you believe it, the reasons you believe the reasons, etc and trying to dig out the whole epistemological structure

This method also has the benefit of forcing you to focus on improving the truth-quality of beliefs rather than winning the argument.

Before you stake your argument on a point, ask yourself in advance what you would say if that point were decisively refuted. If you wouldn't actually change your mind, search for a point that you find more convincing.

This is incredibly hard to implement, because if you didn't have the core belief, the supporting beliefs would never seem important.