Using LANDR as a mixing tool is a great way to get a better mix. Instead of waiting until the very end to upload to LANDR, try uploading your unfinished mix at different stages of completion. LANDR can help expose problem areas in your mix by giving you a sneak peek at how it will sound mastered.
Too much bass? Go back into your mix and apply some HP filtering. Things too bright? Darken things down with some EQ and try again.