If you like to give to different charities (and therefore don’t welcome constant bombardments of letters making you feel guilty if you choose to donate to a different cause now and then), sign up with Charities Aid Foundation. Once registered, you can just tick the ‘anonymous box’ and your details won’t be passed on, but the charity will receive your donation. Charities Aid Foundation also runs a bank account for small charities.
Be sure to only give to small charities that use the donations well, and humane research charities (that use modern kind methods to cure disease, rather than innocent animals).
This is a great idea, following on from Olive, a lovely widowed poppy seller in Bristol. She already had depression, but when she jumped from a bridge, it was found that her kind nature had been taken advantage of by charities who were selling her name on to other charities, resulting in her receiving hundreds of requests each month. She was giving nearly all her money away, because she couldn’t say no.
If you’re a UK taxpayer, sign up for Gift Aid, and this lets charities claim an extra 25p on each £1 donated, at no cost to you. You can include all donations from the last 4 years, but must tell charities you support if you stop paying enough tax (there are special rules for high-rate taxpayers). The government page is complicated to understand, but perhaps that’s the point.