Although your birth data are important to effectively interpret this placement, I will give it a shot.
The placement suggests that you are ambitious and want to achieve professional prominence even if it means competition. Yet, you are not always as practical as you can/would like to be. Much of your professional/public life will be affected by how "other-worldly" you are. This placement also could mean that you are a visionary when it comes to this area. Neptune has a major negative effect which is that it tends to make its native dreamy or dellusional about they area in which it is placed. I hope you are not living in denial when it comes to career or public image. Neptune here may also mean that you dream about doing so many different things with your life that you don't know what to choose or where to start. The worst case scenario is that you don't do anything and just continue to live in your daydreams. Be careful, this could get you do with your life what other people tell you to do... or at least be highly affected by their opinions. An ill public.professional life may be the cause of depression or other psychological problems. But this is only a potential.
A good choice of career would something to do with arts, the movies or something totally humanitarian.
The placement of Neptune in Capricorn will get an entire generation to It have a very practical imagination focused on this world that they see before them.
Watch out for stressful aspects received by Neptune. They will make the bad effects even crazier. The positive aspects will make you seem not too far out there
Hope I have been helpful