My favorite fundamental truths. Keep them in mind if you build something:

(1) It Has To Work.

(7) It is always something.

(8) It is more complicated than you think.

(10) One size never fits all.

And always remember:

(3) With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead.

RFC1925: The Twelve Networking Truths