While you're tracing the object, frequently click the mouse to "lock" the location of the selection before it gets a chance to jump off it. Conversely, you can also set a higher Frequency number so it does this on its own too. You can also adjust the Edge Contrast to a lower number so the tool becomes less "tolerant" to selecting objects adjacent to your desired selection.
I will say this though, using any tool for selecting the "edge" of an object usually prevents the outlined edges themselves from receiving sharpening, while only applying inside the selection. It has been my experience that using the Polygonal Lasso tool to roughly outline the entire
object does a much better job to include the edges, and also saves the time and hassle as noted above from trying to use the Magic Wand or Magnetic Lasso. 99 shots out of 100, the little bit extra included in the selection but outside the object getting some sharpening is going to make no difference to the final product at all, because it's usually sky, shadow, or flat fuselage.
"About the only way to look at it, just a pity you are not POTUS KFLLCFII, seems as if we would all be better off."