Depends on where you were dying: bosses or trash.

If bosses, the first one has some incredibly strong attacks that will squish you if you don't understand the mechanics. When he runs off to a wall and faces the arena, you're meant to stand behind him to avoid a heavy breath attack. You're also meant to not stand directly in front of him, to avoid a strong frontal swipe.
The second boss has damage over time whirlwinds you should hopefully understand not to stay in, as well as an untargetable add that inflicts unavoidable damage until someone (hopefully the healer) shoots it down with the cannons.
The final boss is obviously just about avoiding clear AoE zones.

If you were dying to the trash, one thing to note is the aevis enemies can be dangerous, especially in groups. There's a few areas where pulls can get out of control.

Being level 50 with your job quests done, you should at least have your i90 job gear, so gear shouldn't be a huge problem. It's also worth knowing, if you haven't already, that SV is right around the point where BLM's rotation changes significantly. You're no longer bound to Transposing between astral and umbral. B3 and F3 become your transition spells, allowing you to spend less time in umbral recharging MP, and more time in astral, burning things down.