Chewing is always a difficult problem with puppies, and it's one that needs to be resolved for your pet to be a part of your household. The good news is that most dogs do grow out of their chewing behavior as they get older. The bad news is that they can do quite a lot of damage before they do. There are ways to train your puppy to direct his very normal chewing energy at the right kind of objects, but like any other training, they take patience and persistence.
The first thing you can do to stop your puppy from chewing on your furniture, wallet, remote control, and everything else in sight is not giving him the opportunity. This means you may want to confine him when you're not around, in a crate, kennel, run, or puppy-safe room. Crate-training is the most feasible option for many people, and it can keep your puppy feeling safe and secure when you're away. Whatever space you chose, fill it with safe and appropriate chew toys, as well as lots of comfortable bedding. As your pup spends a lot of time chewing on these toys, he'll start to learn what objects are "his" for gnawing and which are not.
When you are around, watch him like a hawk. When you see him grabbing onto your leather loafers or a chair leg, distract him with some other, more attractive option. When he takes the rawhide chew or nylon bone or whatever "good" toy you want him to chew, give him lots of praise and petting. The idea here is not to punish your dog for the "bad" chewing, but to encourage him for the good behavior. By the same token, whenever you see him chewing away on one of his toys, give him lots of "good boys" and other positive attention. Pretty soon he'll get the idea that the toys are what you want him to use.
You may have to switch his toys around to keep him interested--a rubber ball may do the trick one day, while the next day nothing will do but a sock tied up in a knot. Some household materials can make very good chew toys, but make sure that they can't be chewed into bits and swallowed. An excellent option that will keep almost any dog's attention is the hollow rubber balls sold at pet stores. You can fill them with food or your dog's favorite treat, and he will spend hours gnawing at it, trying to get the goodies out.
Also, if he tends to chew on a surface that is color safe and won't be damaged (like your fingers), you can coat the surface in white vinegar or rubbing alcohol. The smell and taste will make the object much less tempting.
Finally, and most importantly, don't give up on your puppy. It can be hard to retrain an instinctive behavior like chewing, but it's well worth it to have a happy, well-adjusted dog. If your dog seems to resist all efforts to retrain him, consult your veterinarian. He or she can refer you to a behavior specialist or even discuss anti-anxiety medication.