Walk tall and avoid Oxford Street on a weekend. :)

Seconded!

What kind of thing do you want tips on?

You’ll probably develop a Londoner walk – like Nikki said, walk tall (and fast/with purpose).
I’m sure you know this already, but buy a oyster card!
I have lots of restaurant tips if you want, but a good one is Icco’s on the corner of Goodge & Charlotte St – big thin crispy pizzas from £3.50, which is really good value for central London :)
Oh and pub prices will probably make you sad. You’ll get used to it, though the pang of pain when they tell you the price for your pint is never fun.

i love living in london!
jessicav is right you will develop a londoner walk – soon you will be petitioning for ’tourist’ and ’resident’ lanes on pavements…. or you’ll cycle, which the best way to get around !
if you are ever near old street, check out a cafe/bike workship called ’look mum no hands’.
and if you like veggie/ organic food, vita organic in soho is amazing.