If you want a quick and easy lomo look or more accuratly a cross-processed look, you can use the curves tool to apply an S-curve to the red and green channels, Theres alot you can do with curves if you start to use the different RGB channels.
Also play around with layers and blending styles, if you duplicate the image and set blending mode to Screen for instance it will brighten up the pics nicely.
You could blur the new layer aswell and play with opacity, or even add a layer mask to the new layer and mask out the eyes so they stay sharp.
Really you just need to have a play around as much as possible and then find ways to combine tools. Thats the beauty of PS, theres things you could do in it that the creaters have never even considered!
Ade