I could help ya out if you were painting from scratch, but I don't do 'make it look different after it's already done' painting, I do the real deal.
But what I do is also not watercolor style, I specialize more in duping oil or pastel work, not that it's what I set out to do, but it's what happened. Though, I can give you one trick. You set the smudge tool in Photoshop to scatter (and to pressure opacity). Then when you use that over top of color it blends in a way that's kind of like adding water. This'll let you blend in a more watercolory fashion, and then you can add texture with textures later to get that paper and brush look if you want.
So if you want to use Photoshop and NOT use textures that's one way to get the watercolor feel.