Make it easy for both members and nonmembers to donate money to your body. Accept dues and other payments via PayPal. Have a "Donate" button or widget prominently visible on your site. Dues payments can be set up on a repeating subscription basis, which means your members don't even need to remember to pay their dues.
Use the W3C HTML and CSS validators to test your site. Valid sites are likelier to be usable by both human visitors and search engines.
Design your site with accessibility in mind. Simply using standard, validated HTML is a good first step in this direction; this makes your site easier for tools like screen readers (and incidentally, search engines) to deal with. Then consider your choices of font sizes, colors, and so forth. For example, dark red letters on a black background will be all but invisible to many even slightly vision-impaired people. These can be used for striking header and caption text, but consider using a higher-contrast color pair for body text.
Mobile devices account for an ever-increasing share of web usage. Making your site mobile-friendly will improve users' experience markedly. Google may penalize mobile-unfriendly sites in mobile search results, providing another motivation for mobile friendliness. Google Webmaster Tools provides many good measures of site quality, including mobile friendliness. There is also a stand-alone tool for checking individual pages.
If your site includes material that should change over time (most typically, event calendars and time-sensitive announcements), make sure to keep it up to date. A "Calendar of Current Events" with the last event being a year ago sends a poor message about your body. Similarly if you have additional web presences beyond your main page (e.g. Meetup, an auxiliary Facebook page, or the like), make sure to keep them fresh as well. Any time-sensitive web content that you cannot keep fresh should be shut down.
Important announcements regarding policy or security issues will be sent to the usual announcement-only lists used to communicate with local body leaders.
Advisory information, policy clarifications, and technical issues may be discussed on the USGL Webmasters group. Contact firstname.lastname@example.org with any net-related questions, comments, or problems.