Photoshop tools (Layers)

Something that I had to get used to while using photoshop was that you could only edit or move something that has its layer selected, this can have ups and downs, downs being that if I forget to deselect the layer then I could move it accidently, this may be minor but I spent alot of time especially on my masthead getting it perfectly into position, so then I would accidently move it due to the laters and this became frustrating. The advantages of using layers is that you can edit something e.g. erase an edge off of an item and you wouldn't have to take in onto a separate document to edit you could do it on the same page without effecting anything else.