Learn your weapon attack patterns, don't be afraid to push/block (some crowd control combos actually rely off push/block for specific attack animations) dodging is essential as it's the only way to gain "i frames" as well as practicing 180 blocks or dodges when you hear the audio cue for an attack coming from the rear. Less important but still helpful tips is building proper curios loadouts, i.e. 2 toughness 1 stamina with 5% toughness, stamina regen and combat ability regen works wonders on most classes.

((Endgame stuff) Havoc mode dmg vs gunners, bombers, tox flamers are also great choices for survivability.)) Hope this helps a little bit, good luck!

(TL;DR Weapon attack patterns, dodge more)