So I'm playing a sith assasssin and my gear rating is 230 and I'll play story mode uprisings and get like one shotted. I get that I'm not a tank class but I'm just wondering what I can do to maybe take a little bit more damage so I don't die instantly. I'll have a better gear rating than someone with the exact same class but they seem to be able to tank more than me.

This may be a stupid question but any advice would be much appreciated.

With any class survivability is about learning defensive. My shadow/sin are both tanks. If you're dying in any of the solo content though just set your comp to heals. They can keep you alive even if you stumble into a heroic area.

If it's group content, like tactical/veteran fp with no tank or healer it can be more difficult. If it's HM/master fp or ops, you should have a tank and healer so it's more about knowing your role and how to use your defensive cooldowns.

Sith Assassin actually is a tank class - if you spec as one. So it's entirely possible that other player "with the exact same class" is spec'ed as a tank, not dps, and that's why they can take more damage.

If you're specced as dps, don't go charging in first and gatting aggro. Let the tank do that. Then when they have aggro, you can go in and start cutting the mobs down, while they stay focused on the tank.

For more detailed info/advice, check out the class guides on dulfy.net, or in the Shadow/Assassin class forum, here.