One thing that some people swear by is the "tissue trick".
You take a few sheets of clean loo roll and wear them up your sleeve for a few hours, so that they start to smell of you. Then, place the loo roll in their nest - that way they start to associate your smell with a place of safety. Hamsters largely identify people by their scent, as their sight isn't great, hence why this one works.
On that note, make sure your hands are clean whenever you try to handle him - young hamsters can sometimes mistake fingers that have recently been in contact with food for actual food...
Other than that, try placing your hand (not moving) in his cage, and just let him clamber over it, sniff it, etc, still not moving. Try offering food from your hands (treats should be limited, so this can just be single bits of food from his main food - Harry Hamster is reckoned to be the best nutritionally speaking by the way). Once he's used to this, you can try moving your hands a little when he's near them, and work up from there. Small grabby hands must be terrifying for a small prey species, so avoid those for now!
Chances are you'll manage to tame him fairly rapidly, but it's worth mentioning that some hamsters are bitey because they are in cages that are too small and are stressed by it - when they have a larger cage they rapidly stop biting. Another common sign of the cage being too small is excessive bar chewing (which is also dreadful for their teeth). 70x40cm footprint (excluding shelves) is about the minimum size for hamster welfare (there's not a single cage sold in store by Pets at Home that meets this, and only one online), and you can get some large cages that are excellent value for money from Zooplus.