Existence, or "being", is a very simple process of 1) filling up a region of space, and 2) continuing to do so over a period of time.  Note that the space may be very small, and the time very short; alternatively either quantity may be quite large.  For example the universe is, and is quite large and of long duration.  A quantum fluctuation in vacuum, on the other hand, is very quick and small.  As you can see, there is a wide variety of ways to be.

One common misconception about being is that, in order to be, one must consist of atoms or other matter.  This is quite unnecessary.  Such abstractions as sets, ideas, and configurations very successfully manage to be.

In order to be, follow these simple steps:

1. Start by failing to refrain from existing.  This is the #1 pitfall.
2. If you wish to be an abstraction, be sure to be an abstraction which involves or refers in some way to physical objects or abstractions which already can be said to exist.  For example, "the way unicorns smell" just couldn't be.
3. If you wish to be a physical object, be sure to consist of atoms or subatomic particles.
4. Don't forget to last.   Even a fraction of a nanosecond will be sufficient.