Make sure you track the success of your charity's ads. Google provides stats for all your ads to let you see how well they are doing.
Pay particular attention to how many clicks your charity's ad is getting, what the click-through rates are and the average position of the ad. If an ad has a poor click-through rate, bin it, and put that money into an ad that has a higher click through rate.
Try out different keywords, ad copy and costs per click and monitor their impact. For example, run different ads for the same keyword to see which one gets the best click through rate. Also, monitor the conversion rate within your charity's website and try different things on your landing page to boost your conversion rate.
Check out what your competitors (in the private, public and third sector) are doing. Under what keywords do their ads appear? What do they write in their ads? What does their landing page look like?
As a courtesy, when researching competitors' landing pages, rather than clicking on the ad (which costs them money), right-click on the link and select Copy Shortcut (Internet Explorer) or Copy Link Location (Firefox). Paste this link into Microsoft Word. At the end of link it says 'adurl='; the URL after the '=' is the destination URL. Put the destination URL in your browser to view the landing page.