1. Unbox the device, charge up, create an account (e.g. kindle is tied to Amazon.com Kindle Store ecosystem), then register the device(s) to your account for future deliver.
Some content is ready installed for practice in opening, moving around the books, etc. But when ready, collect more content of your own to gain experience.
2. Sources to experiment with
These come in several flavors: paid content from online stores (amazon.com >kindle store, for example: daily specials or promotions mark price at $0.00 sometimes), free content (books considered to be out of copyright and now in the public domain) such as those at http://gutenberg.org in N. America or Australia or other host servers, online articles you have sent directly for kindle wireless delivery, and personal documents you direct for delivery to the device. Many local libraries allow patrons to borrow 5 or 10 ebooks (or audio books) from their downloading service for 14 day periods, too. Additionally, wikipedia has a tool called "print/export" in which you activate a service that lets you add successive articles onto a master list and then finally convert into a single, aggregated PDF "book" for downloading. And if you don't want to read a PDF or print it out, then use the kindle conversion service (or if too big for email sending, then use a free converter on computer to change PDF to mobi for kindle; or PDF to ePub for other eReaders: mobi pocket creator, calibre-ebook.com).
3. Navigation to experiment with
Find Home screen, menus, page forward, page back, Go To (specific page or predefined spot: start, end, Table of Contents). At the end of a session of reading, return to home for a fresh start next time and to allow the device to record the Furthest Page Read. Next time you read, press the Back button to return to the most recent book and its page.
4. Functions to experiment with
From the online store you can choose to Send Sample Now and the dropdown list shows devices and viewing options (read now on your Cloud Reader - depends on a browser and connection; deliver to eReader; deliver to computer registered to the account). You can purchase content, even when listed at $0.00. You can annotate anything you are reading (bookmark, highlight, add a few comments, share to others from your Twitter or Facebook associated account, view "popular highlights" to see to 10 places that other people have frequently seized upon). Reading enhancements include selecting word or phrase and pop-up choices (dictionary? wikipedia entry? google search? x-ray? --but only if so enabled by publisher so that a reader gets an overview of the word or character within the text). Lending your eBook is something publishers can do, too, in which you can direct the file to another person and thereby disallow your own access for 14 days. At the end it comes back to you, as owner.
5. Future steps
a) You have experimented with ebooks from store (purchased when on sale, when priced $0.00 but still treated as 'owned' for your use), from http://gutenberg.org and other online repositories.
Next is to "send to kindle" by using browser add-in: login at Amazon for Manage Content and Devices to add permission for browser to deliver wirelessly to your device; also add permission to your normal email for sending.
b) Now you can do the following: highlight all or part of online article and send/convert for kindle delivery.
c) And you can send a variety of documents as attachments to the Amazon email dedicated to your kindle's services: (subject line) convert. This allows you to email yourself DOC, DOCX, PDF, TXT, HTML, JPG, PNG files separately or in a batch so that the Amazon servers can adapt to kindle and deliver to you wirelessly in a few moments.
d) In addition, plain TXT files can go directly into the device by using the USB cable between device and computer. Just insert file(s) into the f:\kindle\documents folder in order to find and read.
6. Further thoughts
Like any gadget, the more you use it, the more uses you will be able to imagine for it. One consideration is the long view: as more and more documents and publications flood onto the device the performance may slow down. You may wonder how to establish a system of archiving the materials. For titles from the Amazon store, a copy remains online for login and re-delivery. So there is no harm in deleting from device (notes and annotations are preserved for next re-delivery). But for other things: TXT transferred manually by USB cable, rather than via the Amazon conversion free service, periodically (once a month?) you will have to copy files from kindle to computer or other memory (just those since the date of the previous exercise at backing up). That way any deletions can be remedied by hunting on the back up files on computer or external memory device.
7. Links and references
http://gutenberg.org for out of print books now in public domain (not copyrighted after 75 years) including foreign languages and audio versions to download
http://bit.ly/msu2013gpw experiences at editing an eBook to be sold on Amazon (includes several useful links)
http://thekindlechronicles.com is weekly Saturday blog and podcast; http://kindleworld.blogspot.com has a wealth of information and practical advice