Less musical parts have more sonic impact. It might seem counter-intuitive but if you want your music to sound big, add less. With fewer parts, each have more space in the mix and sound more powerful.
When you think you’ve finished a track, play a section and mute each part in turn. Is it there for a reason? Does it make any difference? Or is it just pointless fluff? You might find that muting it does make a difference: the music’s better without it.
If it’s better without, get rid of it (obviously). If it doesn’t make much difference, get rid of it. If you’re not sure about it, get rid of it. Be ruthless.
Don’t fudge it and add stuff to a section that’s not working just to cover it up. If it’s not working, you’ve either got the wrong part(s) or sound. You don’t need more, you need different.