I have 4 DDs - almost 15, 13, 11 and 8. I'm a bit haphazard about the pocket money, so I'm sure they scam more out of me, but in principle this is what we do.
We buy all school clothes, shoes, sports clothes, toiletries etc. Twice a year we get them more non-school clothes, otherwise we plug the gap if they need it (i.e. grow out of something, or it falls apart). If they want other clothes, they have to use their allowance.
We also give the older 3 lunch money (DD4 has packed lunches). They get a school bus, so don't need money for that. We pay for after school activities and school trips.
They then get a monthly allowance (to try to attempt to budget). We worked this out based around £10 a week to allow them to either go to the cinema etc, or to save up for special clothes or music etc, which works out at £50 per month. They also have to buy anything that I don't deem necessary - i.e. make up, trips to starbucks when out, posh toiletries etc.
In return for this, they have to maintain their school work - i.e. any notes home about missed homework etc and they lose that week's portion of the allowance (£10), keep their rooms tidy and make their beds, not leave a trail of destruction around the house, help out setting and clearing the table after dinner etc. I don't feel like I ask them to do a huge amount towards the housework, but they are responsible for their own mess.
In reality, if they have spent all their allowance and it's a friend's birthday at the cinema etc, we usually give in and give them the money give them an advance. Similarly, if they have seen clothes they really want, and tried them on several times, and keep expressing an interest in it, and I approve of it they mostly get it. The allowance gives me the perfect 'out' if I disapprove, or if it looks like an impulse want.
Oh, I forgot to add, this only really applies to DD1 and 2, although now DD3 is heading to secondary, she'll get the same deal. DD4 gets £5 a week, which she mostly hoards.