I’ve noticed threads popping up lately that are full of good advice, so I decided to put a blue stamp on it and see if we can bring all the best tips together.
What’s your best tip for other players setting out to level up on a Hardcore realm?
I’ll go first.
WoW Classic uses layers to help spread out large population of players and prevent any one area of the world from becoming overloaded, which would degrade the play experience. Each layer is a full copy of the entire game world, to provide a sense of continuity with the players around you. When you’re on the same layer as another player, you might see that person repeatedly, in different zones and at different levels, because you’re both on the same layer. The way layering works for groups is fairly straightforward: if you invite someone to group with you and you’re on a different layer than they are, they will be moved from their layer to yours. Thus, when grouping up with someone else on a Hardcore realm, always expect that you’re about to change over to their layer, and be very careful about where you position yourself.
Don’t ever join a group while standing in a cleared murloc camp, or you might find yourself getting viciously mrrrgled.
Never go AFK. Ever. Anywhere.
Just don’t do it. It’s always better to log out and know for sure that your character is safe.
If you really want to hang out in guild chat while AFK, make an alt for that and park them in the city.
In the bank, preferably. Maybe inside the vault, if possible.
My turn!
Be careful of spell casting enemies, their spells can be surprisingly powerful even when they’re at the same level as you. Use line of sight to your advantage. 
The caves in World of Warcraft can give some unique experiences. Feelings of seclusion, trapped behind enemy lines, enemies alerting their friends to your presence, battling a large group of powerful enemies…
I don’t recommend seeking out these feelings in Classic Hardcore.
First Aid. Don’t forget to train it and have bandages at the ready. (Yes, even if you’re a healer. A well-timed bandage when you’re oom can be a literal life-saver.)
Group up for safety— The murlocs and kobolds will.
Autorun is not your friend. (See Kaivax’s rule for going AFK. Combined with autorun, it’s a recipe for sheer disaster.)
Fatigue kills. Don’t push your luck.
Some classes are slightly squishier at lower levels than others but get more powerful over time, so don’t overestimate their power at the start.
Elevators kill. Be patient and time your entry and exit appropriately. I’m looking at you Undercity elevators…
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