Clean the terrace by sweeping it, mopping it with warm water and a mild detergent, and then dusting off all the surfaces and fixtures. The terrace should be as clean as possible prior to decorating.
Paint the railings, walls or fixtures on the terrace to match whatever view you have from the location. For example, focus on lots of greens or browns if you see a lot of trees from the terrace. This makes your view part of the decorating scheme. If your view isn't visually impressive, choose a color scheme that you personally like.
Lay down a carpet across the terrace to preserve warmth and to make the space more comfortable. The color of the carpet should fit your paint job so everything matches together.
Add tables and chairs so people can sit and socialize. Make sure your terrace furniture is made of materials that can withstand moisture.
Hang wind chimes by the door if the terrace still gets wind. Even screened off, wind will still move the chimes and create pleasant sounds as a result.
Add blinds to the outside windows or screens of the terrace if you want to enjoy it at night without being seen by neighbors. This helps preserve your privacy and the blinds can be opened during the day to let in the sun.
Place a barbecue grill in the corner if you enjoy cooking or do a lot of entertaining.
Position planters around the terrace with plants or flowers to make the environment more aesthetically pleasing and to possibly add fragrance to the air.