This is an important step. Focusing on self-image is something that a lot of guys don't care about. Why? I don't know. But it's their loss. To be able to make someone like you, you have to like yourself. You have to be confident with your own image before you can make an impression on somebody else.
There are many ways you can accomplish this. Always look neat and tidy and dress up before you step outside your house. Don't dress up casually if you're going to a bar or clubbing. Put a little bit of effort into your hair and make them look good. You only have one shot to make your first impression. It's up to you if you want it to be good or bad.
