Glad to hear that you are considering this option.
I agree with Eddie that using the crosswalk at Spokane St/East Marginal to head north is the right choice.
My preferred route once coming off the Elliot Bay trail on King street is to hang a left of Alaska Way, right on Yesler, left on James, left to 2nd Ave bike lane.
If you let folks on hear know what time you plan on riding, I’m sure someone would offer to ride with you on their way. You could also reach out to West Seattle Bike Connections to get in touch with folks who would offer to do the route with you.