All magic is basically misdirection. Invisible sleights are simply using the spectators mind to hide a sleight within an action, i.e) turning over the deck of cards, squaring up cards, etc. That said, these are way harder to find since they are less common and are undetected (you literally don't see it). Misdirection is definitely the way to go; some people feel they are bad at it is because they don't really understand. Actually using misdirection is real mastery of magic. I find the best way to test your misdirection is not really to go and test your mettle, but to actually think about what you use as misdirection and see whether or not it seems out of place. Consider an Ambition Card Routine:
"Pick a card"
*spectator picks a card
"Ok now put it back in the deck"
*puts back
Bad misdirection:
"Squirrel!"
"Wow is that a UFO?"
Good misdirection:
"People always ask me how I'm good at magic, and let me tell you, the best magicians use misdirection. I supposed I'm only good at magic since as a kid I was always distracted easily, for example, this one time in school I was --Squirrel!"
"So you choose your card right? Completely free choice? No, don't tell me your card. There is no way I know your card, correct? For the first time ever, what was your card? etc."
Personally, I don't actually have set patter that I would use 100% of the time, try to just go with a conversation and try to:
use questions that make them think usually works best with "do you remember your card?"
take their mind off things "How's it going?"
crack a joke "So I'm now legal drinking age, I walked into a bar yesterday, and now I have a splitting headache, I tried a ice compress, but it still hurts. I don't know if you notice, but there should be a mark right about here."