Here are some basic things that will immediately make you a more proficient Wikipedia user.
Next to the article, remember to check
the Talk page, for any discussion or even controversy — especially for controversial topics, this can be as or even more instructive than the front-page.
the View History, more on this below
various language versions, just to see how the topic has been covered in different languages.
View History
On the View History, this can be a bit confusing — but you can see a number of useful things.
When changes were made
Whether material was added or deleted (plus or minus, in kb)
What they said they did
You can compare versions (that requires some attention to detail)
You see who did what, and you can check their other contributions — or even go on their talk page.
Page Information
Page Information, on the right, allows you to see all sorts of data.
Here are things I look for.
How many people watch the page — indicating a possible level of engagement.
Who created it (this is linked, so I can look up the Creator)
When it was created
How often it has been edited, esp recently.
And then I can check Page View statistics.
Yes — this is fairly basic, but it turns out most of my students (or trainees) have never or rarely checked these options, so definitely worth spreading the word about all these things.
More on Page Views & analysis soon.