Here you can digest how to use Wikipedia in bite-sized morsels. The tips listed below were created for the Tip of the day project, or the Styletips project, but are listed here by title and organized by subject area for your convenience.
To see a list of a user's contributions, go to their user page or user talk page. When you do that, the menu item "User contributions" will appear in the Toolbox menu on the sidebar. This link will show you all the edits that user has ever made (except deleted edits), up to 500 per page. This is useful for tracking vandalism in progress.
Edits with a "top" link are the most recent ones to their respective articles.
You have your own contributions list, which is particularly useful for tracking your conversations on talk pages. If you are logged in, you can access the list from the "Contributions" link at the top of the page.
To help keep track of your discussions on talk pages, you may wish to place the {{Discussion tracker}} template to your talk page.
A good photograph, map, or other graphic in an article can help clarify things. If you want one but are stumped, or totally lost about copyright rules, one really good way to find graphics is to type "public domain" into the Google image search window, along with an appropriate key word. An extra benefit is that you have a high probability of finding photographs that are legal under the Wikipedia rules. (Remember to copy down the artist's name and URL for recent photographs labeled "public domain", because you will need the information when you upload the graphic.)
Of course, you shouldn't forget to look on the Wikimedia Commons first—someone may already have done the hard work! (You can use images from the Commons in the same way as local Wikipedia ones.) Here is the link to Wikimedia Commons search.
For a listing of current collaborations, tasks, and news, see the Community portal. For a listing of ongoing discussions and current requests, see the Dashboard.