If enemy is stronger than you, just get 3 Doran's rings instead of 1. Don't worry about selling them later. Buying 3 Doran's rings is better than being dominated.

1) Let your tank engage 1st

2) Be in the back of the team

3) Focus AP/AD carries (The one who deals the most damage)

4) Don't back out of the fight if being focused. Just do as much damage as you can before dying, u can't run away. Sometimes u might even survive like that. More damage u deal, more health u regenerate.

5)If you get focused often buy Zhonya's Hourglass instead of Void Staff . Let them waste those 2 sec hitting you. It will be good for your team.

Pro's :
[*] Has slow and snare
[*] Ultimate hits multiple targets
[*] Ultimate + Dark binding + Rylai's Crystal Crystal Scepter makes it impossible to escape from her

Con's :

[*] Her two CC's aren't terribly reliable. Dark Binding is a skill shot, so you will need to land it, and Soul Shackles is proximity and time based, so it can be Flashed away before it activates.
[*] Difficult to play; Requires skill
[*] Reliant on Soul Shackles to be effective in team fights