When you have outdoor space adjacent to your house, you can look at it as an extension of your living room, creating an area where people can relax and socialize. If you're planning to eat outside a lot you can buy an outdoor grill and have cookouts whenever you feel like it. You may even want to go to the trouble of building a fire pit or hearth. Even if you just want somewhere to sit and chat with family and friends, choosing the right kind of outdoor furniture is important. You need to make sure that it's weatherproof, which is why waterproof wooden or rust-proof metal furniture is the ideal choice.
If you have a large outdoor space, you can create both sitting and eating areas. By putting down a deck or perhaps enclosing the sitting and eating areas with a low wall, you can distinguish them from other areas, like the lawn. Many people also like to use pergolas to mark an area, perhaps even growing vines or other plants up the pergola's lattice work. This can give a feeling of intimacy and enclosure while at the same time giving a sense of space that still lets in plenty of sunlight and air.
Another thing to think about is how to arrange your furniture. Do you want to simply line up the chairs in a row - to, say, admire the view -- or do you want to interact with your guests? If you think of your outdoor space as somewhere you can actually live, at least in the summer months, you should arrange your furniture just as you would in your living room, with communication and interaction in mind. Make sure to prepare for winter by sweeping up leaves, cleaning up wet spots on decks or furniture, and protecting your garden furniture with tarps. If possible, just put the furniture out of harm's way until spring arrives and you can again enjoy living outdoors.