If you're new to Emacs, after you learn the basics, can navigate around in buffers, and deal with finding and saving files you'll probably start looking for packages that can help streamline your work flow. ELPA makes installing those packages easy but how do you find the ones that suit you?
One answer is the Awesome Emacs project, a community driven effort to curate a list of Emacs packages that people find particularly useful. Each package on the list has a link to some elementary documentation—usually, but not always, a GitHub
README file. A testament to the quality of the list is that almost all the packages I have installed are on it. That gives me confidence that I'll find the others on the list useful too.
You probably won't want to install them all because many are for specialized environments such as Erlang development. The packages are listed by category so it's easy to find packages relevant to your needs. Even if you're an experienced Emacs user, it's worthwhile taking a look at the list.