Making "new" guides seems kinda out of place. Not only is there still alot of information from back then available, there came alot of information up for minmaxing available for both leveling and raiding, ontop of various bis gear lists that cover patch progression aswell if necessary. Wether people like or dislike pservers does not make the various information found on their forums less valuable.
After choosing a race, class and customizing the look of your character, you will spawn in your race's starting zone, usually within a small settlement. Typically, these beginning areas are designed to get you to around level 10 before you leave and move on to the next zone. Right away, you will notice that some NPCs have a yellow exclamation mark () over their head. These symbols will also display on the mini map in the top-right corner of the screen if you are close to them. Talking with these NPCs will allow you to read and accept a quest they have for you. The objectives and status of this quest can be checked at any time by opening the quest log (L). Once you have completed the objectives for said quest, you can return to the NPC (or possibly a different one) to turn in the quest. The NPC whom you need to turn a quest into will have a yellow question mark () over their head. As you complete quests and your character gains levels, always be on the lookout for new quests being offered by NPCs.
Swim Speed Potions (used especially at lvl 37 for Faldir's Cove in Arathi Highlands and lvl 57 in WPL). Try to get multiple stacks of these. I also recommend keeping a stack of these always in your bags. You will frequently pass rivers and lakes and can use these potions to pass them faster through out the guide. Please note that these potions do not stack with Druid's Aquatic Form and Glyph of Aquatic Form.
Warrior should be a go-to choice for everyone who wants to get into the end game. Protection Warriors in Classic WoW were considered as one of the best tanks, Fury talent build was a great option for DPS while Arms were dominating PvP environment. However, Warriors’ strength relies on the character’s gear, which means that you might need to put some hours into finding the right items for your class. It is also worth mentioning, that Warrior might be one of the hardest classes to level up in World of Warcraft: Classic but rest assured, if you’ll manage to hit the level cap and find suitable gear, Warrior is one of the strongest classes in the game.
For the duration of the fight, creatures in the immediate area will not be visible to you (but they may still attack you if they wander too close). Keep in mind that other players will still be able to see you and attack you if you are eligible for player vs. player (PVP). Other players will also be able to view your pet battle in real time, including the pets involved as well as their health as the match progresses.
As you have known, official site had merged three realms into one realm two weeks ago (June 6). Light’s hope will launch new realm – Northdale this week (June 23). Official site is laying out plans for the timeline, and doing its utmost to ensure as smooth a launch as possible. Here mmogah.com will guide you to the new realm – Northdale’s timeline.
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.