Layering layering and layering! If you look at pro pop mixes, there are so many layers. It seems silly until you try it. How do you get huge vocals? Sometimes, it's done by layering up to 15 takes of the same exact line. How do you get a huge bass? Sometimes, you have to layer a grand piano, playing the lowest octave, doubling the bassline and tucked away in the mix. Layering is essential.
Another thing is using delays. Delays, with short times and some panning, can give a sense of space. This works like reverb, but without the muddiness that can come from it.