Being completionist - I find it hard to find like-minded people to complete older achievements that cannot be soloed. Like the 5 rats achievement in Karazhan and others. I know that LFG should be region-wide, but even in the evenings there seems that noone is making such groups. And i have never seen groups for PVP achievements like Alterac Blitz (just as an example -I know that it is impossible now…)
Some time back there was openraid. Now there is literally nothing.
So - any tips on how and where to look for people to group for achievements hunting?
The reason why many people would not be interested in these old achievements is because, well, they’re not just interested, and very few would be even looking in the LFG tool to find such groups. It’s easier to put together a group if you first find people who are interested in doing achievements: guildies, friends or just random players.
That being said, there are indeed communities for what you’re looking for. The most prominent one (in my opinion) is the wow achievement discord: https://discordapp.com/invite/achievements. There are text channels that you can use to find people who wish to do these group achievements: you can look there for others who might be interested. I’m sure there are those who will just help you out even if they have the achievement already as well. Regardless, you should be able to find players to do achievements with considering the members of the discord no doubt share similar goals to that of yours.