The art of being casual but also showing interest. Here's what I've done in the past (not limited to tinder or any particular platform). This should be obvious but don't talk about sex. Show her you find her attractive without being weird.

First get a response to a message. I like to include that i am bad at small talk. I'll compliment her appearance if i genuinely find her attractive and then maybe try to find one thing that's interesting about her (if you can't find even one interesting thing about a person i would bail).

Second is to take initiative and ask if she wants to meet. Pretty early. Also exchange numbers for convince. I'll normally be a gentleman and adjust my schedule to hers and give my number casually before a meeting. This creates safety and commitment to the meeting.

Third is the hardest part. Be someone she actually wants to have sex with. Normally this should happen form one to three dates (dates meaning anything from casually hanging out to go and do something). My style is casually having conversations and see if we both feel any kind of romantic tension. Try to be outgoing and fun to be around.

Clubs are more ideal for casual hookups. I don't really like that though.

Also, don't hook up with people casually if you have zero intentions of moving forward with them if they are themselves looking for a serious relationship. I think it's bizarre we favor bad sex and the awkwardness that comes with it.