MEN: How do I just be NICE to you without you thinking I'm FLIRTING with you?

I know, I know. We're confusing and impossible to predict/understand.

But can it be helped? Are there signs a woman can give you to show strictly platonic interest? Or should we abandon all hope of making male friends without leading them on?

Edit: Wow, you guys rock. Your efforts will not be in vain; I'll sharing this gospel with my non Reddit-ing lady friends and hoping to save you nights and nights of drink-buying-in-vain!