FYI: If you’re returning to WoW after an extended absence prior to patch 5.0.1, it’s possible that you’ll have more than the maximum pet limit and/or more than 3 of a kind. However, this will be the only time that you’re allowed to surpass these limits. You will have to pare down your collection, eliminating your duplicates, in order to add new pets.
If your pet's health gets too low or its attacks aren't very effective against a certain combatant, you can always switch out your current pet with another companion on your team. Only pets that are considered active (i.e., those in your three Battle Pet Slots), may be switched in and out during the battle. Once the match is over, you can always change up your active pet team, which is useful if one of your pets is low on health or dead.
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.
We’re still looking at how we can best deliver an authentic Classic experience at launch, and in the weeks and months that follow - both in terms of gameplay and community. You won’t see phasing (which is tied to specific quests that don't exist in Classic) or cross-realm zones (which combine multiple realms together) in Classic. However, realm sharding is one of the best tools we have to keep realms stable when hundreds of players are swarming the same initial few zones and killing the same few mobs (like they will be at the launch of Classic). To that end, we do believe that some form of sharding may be helpful, especially in those early days. But we recognize that a cohesive world is critical to WoW Classic and are committed to bringing that to you. Layering in Classic WoW
However, after a while the novelty of it wears off and you do start getting a little bored of all the eating and drinking (and wondering why your character isn't getting to Kul Tiran levels of fat), especially if you hop on to BfA for a bit in between. The difference is huge and once you're used to just slamming into 5 mobs and downing them quickly it can get a bit boring to just pull 1 mob at a time and then wait and wait. The really low levels aren't that different between live and Classic in terms of gameplay however, as the small amount of abilities means combat isn't exactly the most exciting thing in either. On live you get past that pretty quickly, but it takes a while longer in Classic (especially if you're playing solo).
Frequently, we are getting many questions from our customers, especially after Blizzard’s announcement about World of Warcraft Classic at BlizzCon 2017, how to farm gold in Vanilla World of Warcraft, currently on Light’s Hope Lighbringer, Elysium Nighthaven and Twinstar Kronos-WoW realms. So, we are glad to share our experience and some knowledge with you. It might be not a discovery for someone but it is good to brush things up we all know and summarize them in one place. We are looking forward to publish more related articles to help and save your time. This guide may help you not in just Vanilla WoW but in any other expansion you are playing.
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.