Any company can give money. You really make a difference by giving time, expertise and energy. You have an experienced, talented workforce - donate their skills, not just pounds.
But keep writing those cheques. Pick a handful of local charities and contribute to them continuously. Set up a matching scheme: match your employees' private donations with an annual cheque to the same charity.
Go local. Avoid the obvious big-name charities in favour of something closer to the ground. Your staff will better identify with it and you will reinforce your place in the local community.
Be sincere. Pick a charity appropriate to your business and really look at how you can help it. Sit down with its managers and ask what they need. Give this the same attention you would a business undertaking.
Keep it up. What you may see as a useful PR or team-bonding exercise could mean a great deal more to a charity. Make a long-term commitment. You may end up getting more out of it than the charity does.
Help your staff give back. Make it easy for them to volunteer. Look into flexi working hours and annual leave specifically for helping with a project.
Choose carefully. Make sure any organisation you work with is a legitimate registered charity and that its values sit well with your own corporate ethos. PETA and Gordon Ramsay, for example, would not be a good match.