Hi. I've been an editor here since the mid-2000's. I've never been inclined to be an administrator and have never applied for the slot. I don't spend much time on it now. It has its good points and its bad points like everything else. You find a wide range of topics here. The pics are good. The lists are nice. I find the most successful articles are the short ones. It was designed originally to be an encyclopedia of short articles. It works best as a quick information resource, I find.
There are a few things to look out for. I think it best if you found most of those out for yourself. I would say, its potentiality as an encyclopedia is pretty limited. The best resources are the books and articles you now find so abundantly on the Internet. Of course, the large number of people working on WP provide a range not possible to paper encyclopedias. WP has something to say about just about everything. On the other hand, keep in mind, the authors are mainly inexpert. Like most inexperts, they are unaware of being so. In order to know that, they would have to be expert!
Plagiarism is rampant. Wikipedia warns you up front that material you write may well be stolen and published under someone else's name. It is best to take that seriously. And, on the Internet, you will now find books of Wikipedia articles for sale. Most of the time the authors attribute these articles to Wikipedia, but often they do not. When I'm trying to do some serious research I exclude Wikipedia from any search. If I just want a few quick facts then I allow Wikipedia.
Then there is what I would like to call botteville's law. For every intrepid band of Wikipedia contributors determined to improve Wikipedia is an equal and opposite band of vicious persons determined to destroy it. Since the only ones who can get away with that are administrators, that is where you will find them. You will not be working on Wikipedia long before you will encounter them. They want you off, so you are not going to hear nice things. People who jerk you around hypocritically are called jerks. That is what you find here.
So, if you start to take Wikipedia seriously as an avocation or a project, you may well be wasting your time. Nothing put up stays there for very long. You might well see a few good things thrown out temporarily like sparks from a fire. Consider carefully, what do you hope to get from this? Is this really worth your time or could you be doing something much more useful to your self or others? I've spent quite a bit of time on this. I did it for the learning experience. You learn a lot about people, writing, and publishing. But, you aren't allowed to contribute any good or lasting material. So, if you were hoping to write something, forget it. Write it elsewhere. If you are a writer, you don't have time for Wikipedia.