Guild Wars 2

Question, do I need to do the story first then go back to do the achievements or can I get them the 1st time doing them?

you didn’t specify which story, so I covered them all.

personal story = are completed the first time (they are only completion achievements).
Living World Season 2 = have to be completed once, and repeated to do achievements.
Heart of Thorns = can be completed first time through (though some you need to repeat to get them all).
Living World Season 3 = can be completed first time through.

ah thank you, ya it was for season 2

Some of the LS2 achievements (maybe all?) have to be done on the same character that did the story earlier. There are also some LS3 story achievements that require multiple instances, since they have contradictory goals.

Usually, you get an icon on your buff bar letting you know if you are eligible, although occasionally, that icon doesn’t show up until later.