Guild Wars 2

What is the best way to farm shards (of essence)? Do they drop mostly from bosses, or regular creatures?

AFAIK, they only drop from trash mobs. Farm trash mobs repeatedly. Solid Ocean, Underground Facility, and Volcanic are good choices.

Thanks!

I usually stick to the beginning of the volcanic fractal. Lots of spawning trash mobs.
You can go leroy jenkins on them, run in, attack, kill, die, respawn and keep attacking. It’s a lot faster than pulling them group by group if you’re a staff ele.
If done, leave fractal, repair armor and hop back in. With one or two magic find boosters, you can easily get around 3 vials / globs / shards per hour even when you do it solo.