Just basic careful play. You're fragile, but you do hit hard if you manage to stack your Fixation (3rd ability). Try to get cultist sacrifice before minute 8 to use it on t3 camps when they appear. You do lots of damage to the guardian (shoot it in the head) with it, too. You don't have any crazy abilities for exchanges in lane fights, but you can try to sleep the enemy with your dagger for your teammate to damage, tho
Lane won
Try to get a few gangs (kills) by using your 2nd ability to come to a nearby lane and be unnoticed (the enemy should be preoccupied with your teammates), then use your 1st (so the enemy won't escape) and finish him with your ult or normal shooting. Use the space created to steal as much camps and sinners from the enemies as possible
Lane lost
Farm as much of your camps as possible. Enemies might overextend, so be ready with your dagger/ult
Mid Game
Try to get one of the solo lanes to farm every wave possible. Try to create space (by pushing the wave) to steal camps. If you have info on all of the enemies then split push and get the walker/part of the walker. If rift is on the opposite side of the map push the wave as much as possible before rotating in time, or try to lure several opponents to yourself so they won't be able to fight for the rift. Urn gives lots of souls, too, so use it for farming and even quicker rotations. If your ulti is off cooldown then look for a gang, but push the wave first. If you see that the enemies won't be able to contest midboss try to start doing it and call it for your team. If there are several enemies trying to get your walker, call for help only when you know you won't be able to defend it solo.
Late Game
When in enemy base ask teammates to protect you while doing shrines/the patron. Through mid and late game you should be constantly farming when not helping teammates in crucial (only crucial) fights. But follow calls from your team