I generally switch the active tool to the Rectangular Marquee Tool in-between using the Crop tool. In that way mistakes or movement of the crop selection won't move/happen. (Using the arrow keys whilst the Crop tool is active will move the crop area borders! As will any accidental drag & drop.) I always manually drag a single Crop tool border when I use it; or from the corner to reduce both the side and top/bottom simultaneously. That is if I haven't already set the canvas size in which case the canvas size will dictate where the initial crop border position will be.

If you are editing a multi-layer image, all processing should be on the upper layers using the Canvas Tool and thus the Crop tool should be used minimally. Why? Because it is far easier to go back in case you have either made an error or change your mind. The upper layers will dictate the size of the image 'if' the Canvas size has been used instead. Once you are 100% happy and finished editing you can then use the crop tool. Using the crop tool will reduce the work-file size as there will be hidden parts of the image outside the canvas area that won't be seen or needed. But only use the Crop tool when you are 100% certain you will not need to reverse any decisions upon dimensions. The Canvas tool determines what portions of the image will be visible.

As I have mentioned many times you should replicate the base (background) layer before beginning editing and processing of an image. You might inevitably need to work with mask, adjustment and effects layers. These layers make it so much easier to adjust or reverse any actions or simply start again from scratch. But once the base (original) layer has been adjusted directly it is very difficult to reverse any actions unless you use history and probably impossible between edit sessions unless you use a recorded history log.