Using +R to prevent unwanted behaviors?

I'm not a professional dog trainer, but I am a behaviour analysis/psych student. Here's my two cents, anyway. Sorry that it's so long!
 
Firstly, I'm assuming that by +R you're talking about non-correctional type training- often "+R" trainers use things other than positive reinforcement (extinction, and negative punishment) to prevent/stop behaviours.
 
You can stop unwanted behaviours by mainly doing two things:
1) Stop reinforcing the unwanted behaviour
- It's important that you consider what is rewarding the dog when it does this- is it the attention? or is the biting/nipping self-rewarding? I think other eople have found that just getting up and leaving the room entirely is quite effective, if the yelp and ignore doesn't work. (Note removing a reward/reinforcer is negative punishment, rather than positive reinforcement)
Also when trying to extinguish behaviour, often the behaviour will get worse before it gets better (called a post-extinction response burst), and that it is not reinforced at all. Rewarding a behaviour every once in a while actually makes it a lot harder to get rid of.
 
2) Reinforcing alternative (and incompatible) behaviours
- Basically if the dog starts biting/nipping or jumping up on furniture, ask it to do something else (that it can't do at the same time as the unwanted behaviour) and then reward for the good behaviour. It sounds like you're doing this already by redirecting, but it might also work without the correction?
 
Another option is preventing the unwanted behaviour from occurring in the first place, although its application depends on the behaviour.
 
I hope that helps!  

I agree completely with Vinia's suggestions. Another thing to remember is that life with puppy includes some less than wonderful things, like nipping, jumping, pee on the floor... it's normal and you and your puppy will make it through. Forgive me if I'm stating the obvious there, but I know that when I had my puppy, a lot of the training literature made me feel like if my puppy did anything wrong, ever, we were both swiftly going to hell in a handbasket - not true. If you ignore puppy nipping it will go away, not instantaneously, but it will.
 
I don't feel that correcting or scolding young, untrained puppies is fair because they don't really know anything yet. It would be like giving you an F in a class you've never taken. Redirection is more appropriate for young puppies, as is training, negative punishment (taking away something he likes if he's naughty, so for example you stop playtime if he's nipping), and good old fashioned patience. []

Is NILIF +R? because thats what i would do []

NILIF encompasses both +R and -P (negative punishment), and yes it's always a good idea to have a NILIF program for any dog. You can start really strict and then let up if you find you've got a very deferential, soft dog, or remain pretty strict if your dog needs the structure.

All the other advice here is also excellent, though I've never dealt with a puppy. I did adopt an untrained formerly-outside-dog of 2 years old and if you think a tiny puppy is hard to ignore, try a full grown coonhound!

the key to using +R to raise a puppy is you have to be very pro-active. Most people are REACTIVE to their puppy-- they ignore the puppy when he's doing something good, like lying quietly, and only pay attention to the puppy when he's gnawing on the furniture or leaping up and gnawing on their arm. One of the roblems with being reactive and using corrections and no on puppies is that the thing puppies want most is attention. Saying NO to a puppy is attention. Giving a puppy a scruff shake is attention. If you accidently teach your puppy that the best way to get attention from mom is to be bad, you are in trouble. The other problem with using a lot of corrections on puppies is it can and will adversely affect the puppy's psychological development and his bond with you.
In general you should try very hard to avoid using corrections with baby animals to avoid causing psychological damage. If you feel you must use corrections with dogs, you should at least wait until they are 6 months or older.
 
Ok, on to how to be pro-active: first, manipulate the environment so the chances of the puppy being bad are very low. For example, don't leave your puppy alone in the room with yummy chairs to chew on.  Next, try hard to catch the puppy being good-- if he's in a room not chewing on the furniture, that's good! praise the pup, play with the pup. Try to exercise the pup before he tries to play with you (which is what he is doing when jumping and biting etc.)-- so catch him doing something good, like not-jumping on you, and whip out that toy and play a fun game.
If he does do something bad-- say chew on the chair, don't get mad, just gently say "leave it" and re-direct him to doing something more appropriate like chewing on a bone. Your most powerful tool for pups being really pesky is withdrawl of attention. Also research NILIF and use it.

I would like to recommend to you, the Ex-pen for your pup. This is a hard plastic 'play pen' for puppies without a floor. The panels can be removed or added to. The area is large enough to put your pup's crate in and the panels are see-through. I bought one of these before my pup arrived and I tell you, it was great! I put a plastic tarp down to protect the floor, put my pup in there with her crate and a toy and she lived the first few months of her life in this area. The pen was in our living room so she could be with us and our other dog could smell and see her but couldn't get to her. Even when my pup was tall enough to jump over the pen, she didn't because that was her 'home'. I finally took it apart and now use part of it to block off my kitchen to keep the dogs out.The pen is only a safe haven for your pup and gives you peace of mind but your pup is behaving like a normal puppy. Puppies 'bite' because that's what they do with their litter mates. When she bites you, let out a loud yelp and that will probably startle her. You can spray bitter apple on your hands and a squirt in her mouth to keep her from biting. She needs to have chewies because she's probably teething. As for the jumping..Keep a leash on your pup tethered to you and when she jumps, step on the leash so it pulls her back to the floor. If you can ever catch her in the beginning of a jump, that's better. When her butt is firmly planted on the floor, praise her but not too lavishly because she might think you want to play.You can correct your pup but only if she knows the command already. When my dog was a puppy and she became 'squirrely', I picked her up with my hands under her front legs and held her away from me. I didn't say anything, I just held her there for a couple of minutes. Your pup is not too young to begin some training like "sit" and "down" and "come".

Follow Vinia's and mudpuppy's advice and you'll have a well adjusted happy dog.  Some others that have responded are encouraging non +R methods that will not be as affective.

The best thing you can possibly do at this pup's age is to get him into a puppy class asap.  He will learn to socialize with, and accept other dogs, and they teach each other about bite inhibition. 
If you are in the US, you can find a positive trainer through these sites:
[linkhttp://www.peaceablepaws.com]www.peaceablepaws.com[/link]
[linkhttp://www.clickertraining.com]www.clickertraining.com[/link]
[linkhttp://www.apdt.com]www.apdt.com[/link] has lots of +R trainers, but anyone can list there - caveat emptor