Know where your money is going.
Pore over the last month's spending from your bank account(s) and write it all down so it is clear where it is going.
Then think about all the things that aren't monthly (maybe insurances, TV license, Christmas / Birthday presents / clothes / haircuts / MOT or season ticket / etc).
If you use cash, try and keep track of that for a week or two.
Once you see where it is going, then it is easier to see where you might be able to cut down.
On pay day, have a standing order to a separate savings account (I know interest is rubbish at the moment, but just a separate account) even if it is quite a small amount. If you aren't broke at the end of that month, you've started a savings pot. If you do need to take it out again, you are making a conscious decision to do so, and need to justify to yourself the purchase is worth it.
Look for best price for your insurances 3 weeks or up to 30 days before it is due - you get far better quotes.
Always worth trawling through comparison sites to check you are getting best deal on all your bills - gas and electric less so in the current climate when they are saying not to change, but generally a good tip in life.
When you go to buy something..... ask yourself if you need it or just 'want it'. If it is in the 'want' category, spend an hour on-line or trawling the shops and markets to see if you can get it cheaper...... then wait 24hours and decide if you still feel it is worth that miuch money
Set yourself targets for saving - whether that is just to treat yourself to a takeaway or something or bigger, more ambitious goals.
In food or toiletries shopping, try replacing what you buy with a cheaper version (shop's own or the 'basic / save' brand) - some things you won't like, but you'll be surprised how many are really nice. Or, if you shop in Coop or Waitrose, try Sainsburys or Morrisons or Tesco, or, if you shop there, try Lidl or Aldi
Look at Moneysupermarket for advice before making any big purchase, and indeed there are forums there for learning how to save money to the nth degree.