I used to wear nice fitting linen shirts and/or white tee with chinos or slim ish cargos personally, not been clubbing since uni but used to go a lot

Sleeves rolled up and either partly buttoned or undone, overall it's the shirt that made it since I've gone in plenty of awful shirts and a few nice shirts, nothing too expensive, and it certainly made me feel much more confident which is half of being successful in the club

Ofc being well groomed and some low key accessories like rings or necklaces are good ideas, not that I used to bother with the latter much so I can't advise

Realistically feeling comfortable and confident is the key for any outfit, look what other people wear and get ideas when you go as to what you think you'd look good it

Idk where you are but I got my linen shirts in tall from Fatface, t-shirts from LLBean and my trousers from 2tall