Okay when it comes to the band account it can be really tricky because you never know which member of the band is tweeting/retweeting. So let's start
1) What's trending
Usually the boys retweet anything dealing with what's trending at the moment related to the band. So my move will be to tweet with that hashtag trend and a picture relating to it.
Example:
The boys Don't Stop music video came out not to long ago. So you would tweet something like this:
Omg the #DONTSTOPMUSICVIDEO was amazing! Im so proud of the boys!
*Insert picture related to Don't Stop music vedeo*
2) Indirects
Okay we all know 5sos are little creeps and like to search themselves on the search bar.
So my suggestion will be to tweet something along the lines of:
5SOS are not a boyband, they play their own instruments for fucks sake!
Use something cheeky and witty. Anything that you think will give them a laugh. Remember they're teenage boys so anything dealing with food, games, music etc (teen related)
3) @ Them
You can always @ the band along with a sweet/funny picture.
Example:
I just ordered the @5SOS ep. CAN YIU HEAR ME CRYING!?
*picture of a band members reaction*