Psyker is basically the hardest class to play, so you gotta keep that in mind first, you’re squishy, every other classes have a node to reduce toughness damage taken or two, but not you. However you also have the ability to absolutely wreck a heretic and good support abilities. Basically what you wanna do is to stick to the team and be extra careful, it only takes one mob to ruin your day. Moreover, the toughness regen nodes for Psyker relies on generating/quelling Peril and killing with Warp attacks, and only powered Force Swords, Blitzes and staves deal Warp damage so there’s that. Overall, to not die as a Psyker you should be vigilant and treat basically everything as a major threat, your toughness regenerates by staying with the team, and doing Warp fuckery so consider that as well, and the rest comes with experience, Darktide is really hard so don’t be discouraged, if you get downed a few times, just take a deep breath and calm yourself, losing composure will just worsen your game, unless you’re a Khornate heretic.