When teaching a dog tricks things to think about are, how are you going to reward your dog, where to train and for how long to make the training sessions.
Rewards basically split in to two categories, food or praise I believe a combination of the two is the best way to go and so I ensure I have a good supply of small healthy treats for the dog.
I tend to use either homemade liver cake or dry dog food. If your dog has dietary issues then consult your vet before you start giving him extra treats. If I am going to use dry food with a dog that has weight issues I tend to measure out his food for the day and then remove a small amount from his 2 meals to give me enough treats for the training sessions, so instead of having two meals a day he is essentially having three meals a day but the same amount of food in total.
Praising the dog is very important, your dog wants to make you happy, you are the leader of his pack and he looks to you for food, warmth and approval. When your dog gets part of the trick right make a fuss of him, this is a good reason for doing your training is a quiet place. The fuss should be over the top, put on an excited happy voice and get down on your dogs level pat, stroke and rub your dog, do not get your dog over excited as you want him to remain focused on the trick you have just taught him and too much fuss will distract him and make him forget what made you happy.
Where to teach your dog his tricks is very important too, you must find somewhere quiet so your dog does not get distracted, noise, smells and people or other dogs are all very interesting to your dog so when choosing a place to train think about these potential distractions. You must also have enough room to train your dog, think about the trick you are teaching, if it involves sitting still and not moving around then you might consider using your front room as a training venue, if you are teaching fetch or some other trick that involves your dog moving around a lot then a park might be a better venue.
Length of the training sessions, if they are too long your dog will get board and your efforts will be wasted, if they are too short then you are not giving your dog the chance to learn the trick before you stop the training. There is no correct time limit on the length of a training session, it depends on your dog and what the trick is, but a good guideline is 10 - 15 minutes and I would tend to do 3 or 4 of these a day, repetition is the key to good dog training so keep teaching the trick even after it looks like your dog has it memorised.