WoW: Classic is scheduled for August 27 (technically August 26 if you're in the Americas). The soonest that you can play it is starting in May, during Blizzard's scheduled stress tests. To opt-in you must have an active subscription on your Battle.net account. If you do, go to Account Management and select the Wow Classic beta. Keep in mind, there will be level caps during the test. The schedule is as follows:
You can also make good gold for opening lockboxes, park yourself in a public place like Ironforge Commons or Orgrimmar near the Auction House, and let Trade Chat know you’re available. You can even make gold by offering to stealth in and pick the Shadowforge Lock open in Blackrock Depths! You’ll need to level up your lockpicking though, so work hard on it like any other profession. Try Redridge, Wetlands, and near the coastal nagas in Ashenvale.
† In the form of electronic Canadian Tire Money® (CT Money®). You cannot collect paper Canadian Tire Money on bonus offers. Any bonus multiplier is based on the base rate of collecting CT Money. Not all items sold at Canadian Tire earn CT Money. The offered rate is exclusive of any bonus or promotional offers or redemption transactions. CT Money is collected on the pre-tax. Bonus CT Money collected from online orders will be applied to the member’s Triangle Rewards™ account within 5 weeks of the purchase date. Terms and Conditions apply. Visit https://triangle.canadiantire.ca/en.html for more information.
The system is automated, meaning that once slots are available, beta testers will be chosen, without any beta key to speak of. Kaivax then goes to stress the importance of your account security, stating that, “any third-party e-mail messages, websites, or in-game whispers that offer beta keys or access to the WoW Classic Beta should be considered illegitimate and ignored or reported.”
This tutorial will ensure that the beginning of your journey will be a smooth one. It provides information that will help you find your way when you get lost, as well as tips that will offer guidance and advice as you march on towards greatness. It is not an exhaustive guide, however; it neither can nor wants to unveil every secret of Azeroth to you. That glorious task is left up to you as you explore the world yourself. Think of this guide as a touchstone for your early adventures: enough to get started, but too little to spoil any of the awesome surprises that await you in Azeroth.
Only really to expand on Gráinne's comment as regards the 'collecting' and 'roster development' sections - which are, as said 'distinct' although they are intrinsically linked - I would like to point you in the direction of the in-game Achievements > Battle Pets > Collect tab. There are a series of achievements called Raiding With Leashes, pretty much all of which can be completed via the auction house - if you have the gold/inclination - or by completing old raids.