The easiest way is to have this done automatically. Have the bank save the money right off the top for you and don’t even involve yourself. You already know how much you want to save in the year, so if you’re paid monthly, then divide that by 12, and if it’s every 2 weeks then divide that by 26.
Then, either online or by visiting your bank (depending on how they do things) just have them set up a transfer effective the day after payday into your new account(s) - which we’ll get to….
Make sure it’s the day after payday so that the money has arrived (from wherever you get it) but you haven’t had much chance to spend any. Leave it too late in the month, and you may not have enough left. Do it early in the month and you may not even miss it!
Of course this assumes that you’re paid regularly and that it goes to a bank account in your name. If not, you may need to figure out a way round that - but the principle remains the same. About 10% of your regular income is put aside each time you get it.
Where does it go? Well the idea is that you set it aside in the bank where you won’t touch it. You also want to try and ensure that you’re getting some sort of interest paid on the money you save too - so that may mean looking around for different account types or even different banks. If you’re going to have to do this, don’t restrict yourself to the high-street, there are some good online banks as well. ‘ING direct’ comes to mind as one online option (No, I don’t use them, they just advertise well in my area).