Okay... a few ideas.
Leash him to you with a fairly long line , so he's always following you around, but let him approach you more. You need to work on calming signals... for some reason I am not finding my usual link, but this may help
Calming Signals
Two dogs, strangers to each other, meet at the park. Rover slowly blinks as he averts his eyes and sniffs at the grass. Fido yawns. Rover looks toward Fido, flicks his tongue and then moves in a wide half circle towards Fido. Fido flicks his tongue in response, then approaches Rover and sniffs him. Rover stands still until Fido is finished and then he sniffs. Fido goes into a play bow (front legs extended, butt in the air) and the party is on. They romp and play and growl and bite and have a wonderful time. Neither has had enough exposure to other dogs to be well skilled in social nuances, just enough to send calming signals and an invitation to play. More experienced dogs will produce an entire range of eye movement and body language in a few seconds, communications that most humans don't even notice, and commence to playing (or fighting!) in quick order.
We can use these signals to our advantage. Tongue flicking appears to have a number of closely related meanings. Frantic flicking can mean "I'm very, very nervous! Please calm down!". Less frantic flicking seems to ask "I'm nervous, but I'm coping, are you OK?". Dogs noticeably relax if their tongue flicking is answered in kind. A simple lizard impression on our part can go a long way towards telling the dog that we mean him no harm. When handling a very nervous dog a stronger way to get the "I'm OK, you're OK" message across is to tongue flick and slowly blink, or blink and yawn or any combination of these things.
Some dogs never see anything other than their own homes, their own back yards and their own people. The social skills of these dogs are going to be poor. They may not recognize calming signals since they've had scant opportunity to learn them or practice them since leaving their littermates. They may also be so overwhelmed by the strange atmosphere and people that they are incapable of calming down even if they do recognize the signals. Conversely, a dog who's been throwing signals at people for years and receiving intermittent (even if unintentional) positive responses may over-exaggerate his body language and calming signal usage.
Forehead massage is a very effective means of calming. I think it is a successful method because it feels good and is an indication that no harm is intended.
What must they think of us? Why would any dog allow himself to be put on his back on an x-ray table, by two strangers, and have his legs stretched out? Why in the world would any animal allow us to poke needles into his skin? I've come to believe that well socialized dogs learn that humans can sometimes be very weird. We do completely outrageous things without adverse effects to the dog. They learn to be tolerant of our weirdness. Those that are not tolerant are only displaying normal canine behavior, not something odd. We're the ones being odd.
The bottom line is that we are strangers to the dog. We are not pack mates. We are not a known quantity. We are the unknown, the unsafe, a perceived danger. We cannot arrogantly demand that they cooperate with our efforts to put them in very uncomfortable situations. If we try very hard, what we can do is communicate our promise to "First, do no harm".
1999 Deb McKean<<
Kathy Diamond Davis is excellent with fearful dogs.
http://www.veterinarypartner.com/Content.plx?P=A&A=1612&S=1&SourceID=47
For all her articles:
http://www.veterinarypartner.com/Content.plx?P=SRC&S=1&SourceID=47
But one of the best things is to begin basic obedience training, setting up things so you make contact learning and rewarding to the pup. Use treats, praises, whatever he responds positively too, and keep on a long line so fleeing isn't an option or becomes a habit.