The universal correct form of greeting between strangers is
‘Now then pal’.
It is a heavily nuanced phrase, full of hidden meaning and lethal traps for those not versed in the subtly of intonation. In fact phrase is the wrong description, it’s half way to being a language in it’s own right, parts of the town can socialize using just those three words for hours at a time.
To be greeted by a cheerful ‘Now then pal’ is a good start.
One meaning roughly translates as, “We both know this could kick off at any moment, but what say we keep it friendly?”
And until you gain confidence in the language your best option, in fact the only permissible option is the universal response,       
‘Now then.’
This should be delivered in the most neutral, deadpan manner you can muster.
This commits you to nothing and keeps all your options open.
And you need to keep your options open since an alternate meaning of a cheerful ‘Now then pal’ could easily be ‘so this is where you’ve been hiding’. This has a lot of implications for your well-being, you may owe the speaker money, slept with his wife or 'knocked off' his bicycle.
Stealing bikes in Hull is a crime on a par with cattle rustling in the American West and carries a similar penalty. Hull has the record for the greatest number of people found drunk in charge of a bicycle than anywhere else in the country. This is a town that takes its bicycling seriously.
It is crucial that you get your first response to a greeting right, as King Charles I found to his cost when he approached the city gates in 1642.
He was greeted with the customary “Now then pal” from the battlements but failed to give the expected reply of “Now then”, and had the city gates slammed in his face as a result.
Many historians credit this act as signalling the start of the English Civil War, and so reinforces the thought that in this town visitors should choose their words carefully.
Greetings between friends are very simple.
Just drop ‘pal’ at the end of the phrase and add your friend’s name.
It’s impossible to read anything into the intonation at this stage, and it’s not necessary. You could have suffered a bereavement, lost your job, found out your wife’s just left you, won the lottery, it’s all immaterial, of absolutely no importance.
“Now then Dave” signifies a completely non-judgmental and open-ended greeting.
In a town that keeps its cards and dominoes close to its chest her people can’t be doing with the cheery and often insincere “Hi how are you?” much favoured in other parts of the country. This is considered suspect to say the least since it puts people on the spot. Are you really going to give them the list of things wrong with you? And would they be remotely interested?
No, it’s far better for the person greeted to be given a breathing space, a chance to decide what they intend to talk about and which way the conversation should go.
Just simple politeness really, and “Now then Dave", or whoever on first meeting does it just dandy.
It’s also a very democratic form of greeting, allowing for no ‘airs and graces’, used by all classes and ages. I remember the shock of hearing 14 year old Ellie whom I’d not seen for some time, greeting me with “Now then Dave” in the same low, deadpan tone used by her dad. She was signalling quite plainly that any further conversation would be conducted as equals, she was no longer a child, she had come of age.
If you are unfortunate enough to hear “Now then” with the stress on the first syllable being slightly leant on, this should give you cause for concern. A line has been crossed somewhere, and a warning is being given.
It’s more easily understood as a command given to children by their parents, “Now then, if you don’t stop what you are doing right now, you are going to get smacked.”
The more sophisticated grown-up version has reduced that sentence to just two words.
Best advice here, if the words are directed towards you, is to review your sprinting times. If they seem wanting, you could always offer to buy a round.

So there you have it, a few tips on how to behave on meeting people for the first time in this fair city, naturally after closing time all bets are off; anything could happen.