Before you get dancing edge, dnc low lvl solo can be slow at times. Dagger ws are quite horrible before lv62. One way to combat this though is to use h2h for combo and later on raging fists, which are strong ws (the skill gap isn't very wide until lv60+ but afterward you will need your daggers). If you have an npc buddy though it'll make solo play much faster as you can set them to attacker mode and let them do their work while you cure them (need to make an <stpt> or <st> waltz macro to target them though).
Invites when I lvled weren't brd or cor fast but probably more blu-ish in desire. When you exp you need to keep in mind that you're almost always invited to help make the pt run smoother by curing, debuffing, and even sometimes co-tanking. You'll get a chance every so often to show you can put in fair numbers (sometimes great numbers), like when your pt is running smoothly enough for you to burn a little tp on ws.
At endgame... it's rough. There are a good few spots where dnc is pretty handy, like dynamis, some limbus floors, small group things (assaults, nyzul, salvage) and some low-man stuff. Your task here is support first and DD second. But as much as you can support others, dnc still has a somewhat negative view at some things. This is where showing your strengths and leaving good impressions of your skill with the job are needed the most in order to let you use it more. It can even lead to unconventional uses of the job, something you'll need to think on and find solutions for when the situation requires it.
The best advice I can really give to someone looking to lvl the job is to try and enjoy it. Have fun with it. Some people in ls laugh when they lvl it for subjob and they hate the way they look doing waltzes and stuff, while others like myself actually enjoyed what it could do the whole way up. Whether it's keeping an insanely strong sam/war friend alive at mamools (right beside gc camp), campaigning and earning my lost ranks back by tanking with it (been lazy keeping up with them), or doing random stuff with my friends on it for big cure support and fairly decent dmg, I continue to enjoy the various things I can do on dnc.