I have noticed in registrations for the MIT Fall competition that many, many people do not fill in a WCA ID. In the current system for registration pages in the WCA database, this seems very easy to miss; people don't bother searching for their name since there's not much information to be entered. I suggest two alternatives:
1) Add a field for WCA ID; do not make a person search for and load their name in order to put a WCA ID in their registration. This has the downside of having to explain what a WCA ID is. On one registration form I made, I explained it as the last ten characters of your page's URL. Some people put stuff such as REYN01#444 (which would be the last ten characters of the URL if you clicked an anchor link). On the other hand, WCA ID is listed in the personal information at the top of the page.
2) As someone types in their name, automatically search for matches, so that the person does not need to go to a separate page to search for their name. We can still have all the fields listed like gender and birthdate, but put above them "Fill this in if this is your first competition". This will certainly be a harder solution to implement, and I am not skilled enough to suggest how to do this, but if anyone could implement this I believe it would work well.