One of the main questions would be whether the party already has arcane casting support. If not, I would leverage the same advice as I do Eldritch Knights -- don't be afraid to let your base class be most of the answers for 'what do I do in combat?' while your spells add to your general utility. Spells like Comprehend Language, Enhance Ability, Invisibility, Knock, Mage Hand, Mending, Message, Minor Illusion, See Invisibility, Suggestion and the like are useful for every party, and if no one else has them, grab one or two.
Beyond that, shore up weaknesses you have, or things other sub-classes would have given. If you don't have Darkvision as a species, grab it as a spell. Since you don't have a shadow-monk's 60' teleport, pick up Misty Step.
After that, yeah, Blade Ward, Enlarge/Reduce, and Shield are all combat-useful. An AoE like Shatter might be useful, but it's hard to say. Certainly up close one punch to each goblin quickly outpaces Burning Hands. If you pick up Hex/Hunter's Mark from somewhere, getting extra slots to use them with while still advancing as monk is also pretty nice.