Just like humans, a dog’s hair can be normal, oily or dry. Run your hands backwards through your dogs coat and feel the skin: does it feel greasy or dry?
A dog with a normal coat of hair and skin can probably do with a wash every two weeks.
You can bathe him, use a hand shower, a bucket and sponge, or use a hydrobath that will come to your home. Be careful around the eyes, ears, nose and mouth, and try to avoid water dripping into the ears, as it can contribute to ear infections.
There are some excellent images at Pinterest that demonstrate grooming techniques, especially cleaning your dog’s ears, and clipping his nails: