Your spell Hex adds 1d6 damage to attacks you make. This includes Eldritch blast and Scorching Ray. Make sure that you always have Hex up, as long as you aren't in danger of losing concentration. You only have to use one spell slot on it, because once you kill someone who has been hexed, you can cast it again for free on another enemy.(Make sure you use re-apply Hex spell, it's separate from Hex.)
If you have a target that really needs to go down, Scorching ray can deal 9d6 to a hexed target.
Take the invocation that adds Charisma to your Eldritch Blast for an extra 3-4 damage. You should boost your CHA at level 4. It will give you more accuracy and damage. You don't need to worry about weapons, because you will almost never deal more damage with them than Eldritch Blast.
Don't forget you regain spell slots on a short rest.
