General thoughts on Registration
Treasury interface is frequently an issue. I remember years of fighting about whether all checks must be seen by the treasurer, and years where we photocopied every check. There is information on the check that helps registration get the right information into the database, it's important they have this information. I've run a number of conventions quite successfully using a system where registration directly makes the deposit, and turns over records to treasury showing how many registrations of what type were in it. At that time, the registration software I wrote produced those reports.
Checks are presumably getting less common. What are current proportions of checks vs. PayPal vs. any other payment forms?
Speed in cashing peoples checks is frequently a problem. I hear people grouse about this nearly every single year. It confuses people, makes us look unorganized, and exposes the checks to opportunities for loss and theft. For Minicon 27 we set ourselves a goal for maximum time from PO Box to deposit, and essentially met it.
Confirmations should be sent relatively promptly, not just in a big batch at the end. Again, it's a question of looking organized. Given people's usual organizational skills (our members' skills), it might be a good idea to also send everybody another confirmation right before the con.
Plan the interface from registration to badge-making! Test it before the last second!
Plan ahead on whether there will be registration "packets" or not. The question comes down to how much delivering of specialized stuff to members should registration support.
Plan ahead on how to attach programming schedule labels.
(Somebody whose experience is more current than mine should talk about what we think are best practices today.)