Jump in anywhere! Find the task or technique you want to learn from this list (for example, Update Query Results). Note the number in the blue oval (51, in this case). And then just flip through the book until you find that same number at the top of one of the pages.
Each short lesson lists any techniques that might be good to know as background (✓ Before You Begin) as well as other lessons that may be related or that might give you more information (→ See Also). Have fun!