The first application I wrote using asp.net started off rather small,
and as a result, the design of the application took a "Rapid
Application Development" type of approach. By this I mean that it was
simply built using a simple 3 tier architecture, where the interface
was created using css and master pages, the middle layer or business
logic classes, consisted of some simple public classes that defined
some of the business rules, and the underlying data layer contained
all the stored procedures and database schema. Everything worked fine,
since it was a rather simple application, and it was only being used
by a few people. Well, as some of you may already know, after each
demo, the new requirements kept getting added to the application, and
now it is turning into a huge application that is expected to be used
by hundreds of people. Incorporating a design pattern into the
application would have been a good idea, but I was not familiar with
some of the patterns when I started writing the application. I am also
not experienced with thread safety. Considering I am limited on
time(only a couple of weeks(2 or 3)), what are some things you experts
can suggest I take to prevent some unforeseen problems? FYI,  All the
classes in my app_code folder are declared public. Nothing is static.