Ride, ride, and ride. Start on property or in the arena and move outwards as you feel comfortable, even if it's only 10 ft further than you went the day before.
Don't allow yourself to be scared, if you're asking this question you're probably feeding into his anxiety. That isn't a cut, I've been there and I know several other riders who've been there with spookier horses.
It helped me to talk to him a ton. I jabbered my mouth off and I made sure that I laughed at him when he started spooking or getting tense. It helps to sit a little deeper and really wrap your legs around him too. Hard to explain, but basically you're supporting him with your legs and reminding him that you are there and you'll take care of him. Try not to choke up on the reins as that'll just make him feel trapped, just keep thinking "relax" to yourself and either talk, sing, or laugh.