Most puppies bite and chew their owners, and even growl, especially when they are playing. Some owners worry that this means the puppy will grow up to be aggressive and start to impose punishments or strict dominance regimes. Other owners do nothing, assuming that the puppy will simply grow out of it. In fact, the best approach is somewhere between these two.
The biting is, of course, completely normal puppy behaviour. It has two main causes:

• puppies and dogs play together by fighting "mock battles" in which jumping on an opponent and biting are fair moves. They do this with their human families too, until taught otherwise

• as they begin to lose their milk teeth and grow adult ones, puppies often feel pain in their teeth and gums which may be relieved by chewing.

Puppies need to learn while they are young that it is unacceptable for their teeth to meet human skin under any conditions. They may think anger is the human way of playing rough, which is why punishment won't work, but the following should get a result.
Make sure your puppy has some very hard toys to chew at to relieve teething pain. Smoked bones, which can be obtained from the pet shop, are good for this and less messy than fresh ones. Putting them into the freezer can help too, as chewing them cold often seems to relieve the pain.
Your puppy will be less likely to bite if you don't let it get too excited. Keep play sessions short and try to stop before the trouble starts.

It can also help to play structured games which are less confrontational than pulling and tugging ones.

Dogs dig for many reasons, and sometimes it helps to pin down the right reason before you take steps to alter his habits.
I've used "he" to refer to the dog throughout this article but most of the points apply equally well to bitches. The only one that doesn't is hormones. If your dog is male and there is a bitch in season near by, he may be trying to escape from your garden by tunnelling. If your dog is female, especially if she has recently had her first season, she may be showing "nesting" behaviour. If this gets very frantic you need to have her checked out by a vet in case she requires medical treatment to help her get over it. Either male or female hormone-inspired digging can often be reduced by neutering.
Otherwise, the reason your dog digs is most likely the simplest explanation - he is a dog. It's very normal and natural behaviour and many of them go through at least a short time where they do it regularly. If he's a puppy, he may grow out of the digging as he gets older (my own puppy is nearly twelve months at the time of writing; he hardly digs at all, having been a very keen "gardener" at first). You could try waiting him out, or you could read on.
If it's a very recent habit in an adult dog, especially if it only happens in one place, then probably something specific happened to start him off and you may be able to distract him out of it again. Check that there isn't a toy or bone buried in the spot, or that rabbits haven't made a home there. These are usually used to stop puppies chewing indoors but can also put them off particular areas outside. It might also help to block his access to the spot for a while till he gets out of the habit. A pile of large stones or rocks, or a temporary wire netting fence round his favourite digging pit may do the trick.
If he is adult and it's a long standing habit (or if you try all the ideas above and he simply moves to a new spot) it's easier to limit his activities than to prevent them altogether. Digging is, as we said, a natural doggy behaviour.
Try giving him a small area in the garden where it's OK to dig and nose about. Dig out the plants and put in loose earth or sand, then bury a couple of biscuits in it. Let him see you the first time so he knows the food is there. Tell him he's good when he digs it out. Refill the area with biscuits, toys or bones every few days and praise him when he finds them.
If it is impossible to give him a digging area, vigilance is the only answer.
A final word - but you knew this already, of course - NEVER try to put him off digging by burying sharp objects where he's likely to dig.