This shows that you know how to have a great time, and can provide him with excitement. It’s easy to invite someone out for a drink or dinner, but the most memorable people are the ones who invite us to do something we’ve never done before.  Don't get discouraged if he turns you down. You can simply say, "Well, if you'd ever like to go in the future, let me know. I'd really enjoy that." This keeps the door open and puts the ball in his court. Make it something you’re excited about. If you’re afraid of heights, don't invite him to go ziplining just because it sounds cool. If you’re having lunch or hanging out right after work, you won’t be able to completely change your clothes. But you can make small, flirty changes. If you’re getting together on a day off, be sure to let your personal style shine, since you don’t have to dress for work.  If you’re going straight from work, consider letting your hair down after having it up all day. If you’re taking your lunch together, you could leave the jacket of your skirt suit at the office to show a less formal side of yourself. It’s okay to change your clothes between work and happy hour. If your clothes are dirty after a day of work, it makes sense to change before going out. If you’ve talked during the day, you can remind him of your connection by sending a short text or e-mail. Try to keep the conversation not focused on work, but instead on something you connected over.  If he mentioned a band he likes, send a text that says, "Hey! I downloaded that album you mentioned. Thanks for the awesome recommendation." Keep it brief. Even if he likes you, he may not want to be reminded of his workplace once he’s done for the day. Don’t expect long texts or e-mails. Make efforts to be friendly with the people you know he hangs out with. They don't need to know your intentions, but if they like you, they’re more likely to support a budding romance between you.  If he’s friends with some of your coworkers, this one can be easy. Remember, people tend to value their friends’ opinions, especially when it comes to relationships.

Summary:
Invite him to do something different. Wear something you couldn’t wear to work. Check in outside of work. Get the approval of his friends.