15-20mph is ideal to learn. Lower your boom slightly. Start waist or shoulder water deep first. Sail needs to be as upright as can manage before you try to stand, point board between 45 degrees downwind to 90 degrees across wind. If too early all the wind goes over the top, far more power when nearly upright. Reach arms high as possible, throw up in one move for momentum. You can also use front foot first not just back. Be as close to board as you get. Foot on its side roll foot over stand up!

>= 15 knots

depends on your weight but at least around 14-16 knots

You can do water start easily when it’s enough wind for planing or you can do light wind water start if you need some more wind to get planing