Tried and true
My boat is a Tartan 27, full keel with a centerboard. The centerboard is useless at the slip, though as I have just under 4 feet of depth at low tide. I don't have a lot of prop walk, but when backing my turning radius just about doubles. If I need to turn more quickly than the boat wants to while backing, I bring the rudder across to the opposite direction, as it passes midship I shift to neutral and then forward. When the rudder is in place I give a short (one or two seconds) burst of power to "kick" the boat further in the desired direction, and then reverse the process so that I am backing up again. The downside is that you lose some speed astern, but you can effectively pivot around the center axis of the boat briefly.
I mostly single hand nowadays and the best thing I ever learned about my own slip is to rig ratlines on both sides. More often than not I simply use the pilings and lines to walk the boat in and out of her slip. It's very controlled, very calm, and it always works, even if the engine cuts out completely. Obviously this is more difficult if you are coming into a transient slip, but it can also work in that scenario if the conditions are not too bad.
My advise is get out on the river (lake, whatever) on a calm day. Pick a visual point of reference that is as close to you as possible (a day marker works great for this if it's not too crowded) and practice maneuvering under power for a while. You need to know your boat and what it can and cannot do. When it comes time to dock, go slow, plan out every step ahead of time, and then execute your plan.
I am back in the slip that my Grandfather had built at the local club for the boat that I now own. That slip has been there over 20 years and I have entered and exited it more times than I can count. To this day I can occasionally be seen rafting along the outer pilings to the slip (parallel to the main pier) on occasion just to buy enough time to get things right in my head and on deck. I come in to the slip with docklines on deck just as if my permanent lines did not exist so that I have options without needing crew.
Take your time, plan the maneuver, and practice practice practice. I was forced to practice by my granddad and dad as a kid and I can't thank them enough. My pride is worth a hell of a lot less than the larger boat in the next slip.