Hello and welcome,
The biggest tip I can give you is to be concentrated on what you farm and level up. Just levelling up characters because you have them is not the way to go.
You could have a perfect team and a terrible team at the same GP and the perfect team would beat a million of the terrible team.
So find out which characters and teams are good and which aren't. There's no point working on those that aren't.
Lastly look at the journey characters. Legends and then galatic legends make teams great. So see what you want and are viable and work towards them.
So in short, do your homework and prioritise.
Night Sisters is an ok team. You'll get use out of them for your whole SWGOH journey for sure. They don't lead you anywhere though.
Daka is essential to Night Sisters. Acolyte.......well she's lost favour in the last few years. Her strength is her stealth (being invisible). If you use that with the zombie that doesn't die if another NS is alive..........it's a not bad cheese defence, but a bit old fashioned now.