Playing with other classes, Message and Mage Hand are great ways to start trouble or buy time until trouble starts anyways. I expect a Warlock can do same with them.
If your group's classes require coordination, Message is a must-have.
Vicious Mockery is useful if you are fighting enemies who retaliate against melee blows.
If you want to play against type, search out a cantrip that heals or provides THP, even if only a trickle. The DM (and therefore also the monsters) will be surprised when you help somebody else get back on their feet and into the fight.