When should I write Static Methods?

So I understand what a static method or field is, I am just wondering when to use them. That is, when writing code what design lends itself to using static methods and fields.

One common pattern is …

Create UML diagrams after or before coding?

I can clearly see the benefits of having UML diagrams showing your infrastructure of the application (class names, their members, how they communicate with each other etc).

I’m starting a new project …