What you can do, and for people who don't know this trick and see you working this can seem like magick, is to add a new layer above your pic, and add layer styles to this empty layer.
Then, whatever you do on it, like painting, magickally gets the effects applied to it, be it a line, or a selection or...
See, the effects are free from the object, but every object on the same layer will take them.
When you rightclick (Cmd-click on the mac) on the small f icon in the layers palette, the one that indicates that the effects have been applied, you get a menu, and on here you can choose "create layers". This makes a separate layer of every effect. You can also choose Global Light to change the direction of the light (very useful for anim gifs) and Scale, which allows to make the effects smaller or larger.