Aweaver, you can enter a person into F1 with just their name and no other information. That way you can at least get your numbers correct and THEN tackle the process of obtaining that person's information. There are a couple of things you could also do:
In our childrens ministry we have several separate places for people to sign in, some for regular attenders and some for visitors. This way the regular attenders just sign in and the visitors are required to fill out information cards.
If you go ahead and put them in the system with just a name, you can also add 'NEED INFO' as an addition to their first/last name(or middle, if you ask for that part of their name in the reports) so that when the rosters are printed out, the volunteers working will be able to spot the people whose information is incomplete and ask them to fill out their cards then. I know some people aren't so keen to this idea because of the addition to their name that then has to be removed later, but for your purposes, it might help.
Hopefully this will help you out a little!
Whitney Storey
Database Manager
East Bayou Church
(337)-984-8291