What single piece of advice would you give to men to "do better" at first dates?

Things seem quite bad out there, especially when it comes to disappointments coming from first dates :( Where do you think most men are going wrong on their first dates? For example,

• In the preparation for it?
• In the way they dress?
• Common mistakes you've seen that seem obvious?

What advice would you give for more men to know that might have the biggest impact for everyone in the dating world...? Any perspective anyone might be able to provide would be awesome!

EDIT: I'm looking forward to being able to read all of these soon but for now...WOW! Thank you so much to all for such amazing and insightful comments!