Any guidelines on application stucture/Start up mode?

[Alex]

Hi I am trying to find out what the best way to structure a .net application
is. In the past using VB I would call a Sub Main procedure and setup a
controller class which kind of held a reference to all the other classes. I
would then create a main form (from sub main) which could access and class
through the controller class which was stored in a module.
This format worked quite nicely because it made it easy to seperate most of
the code from the UI.

Since learning .Net I have not really been able to find any advice on the
best way to set the structure of a basic application.
p.s. I am writing in both vb and C# however more in C#

Any ideas appreciated

Alex