Should I flirt or stay cool, calm and collective?

So I have now been single after a 15 yr relationship with whom i thought was "the one", only to be let down, but im good. I've been single for 7 months now and am very much ready to move on but feel out of touch with the dating game. I've been out approaching women for months now with almost 0 success and i feel im doing something a bit off. I think after the breakup, I've been in this mindset of not wanting to appear needy and desperate, thus, enacting this "tactic" to appear cool, calm and collective. In doing so, I tend to get phone numbers, but I notice that every girl eventually faded away from socializing with me

Before my "marriage" I was a teen. I would flirt with girls i like and often did this as a means to kiss her or whatever. I feel I had a much higher success rate finding a girlfriend or having relations by doing this and I think its because I establish sexual tension and interest in her almost from the beginning.

There's a girl i like now. I've invited her out a few times to no avail but she keeps letting me know she's single and okay with hanging out, but never does it. One time we drank together, from her inviting me, and I felt like she was flirting with me but I didn't want to make things weird, thus, incorporating this cool attitude. She literally was in a bathing suit standing in her doorway at night talking to me. I tried to invite her for drinks after this which she agreed but it never ended up happening.

Next time I see her should I try flirting with her to show my interest? I've been told by one girl that im not trying enough and one girl after sex a couple times, said the same thing. Maybe Im not flirting enough with women i like.

Is it better to be flirtatious with women showing interest in them, or just "hang out" and wait for her to show interest first? Im starting to lean towards the first option as it keeps u out the friendzone and builds tension and the second option apparently lands u as a boring friend which then gets ghosted.
Should I flirt or stay cool, calm and collective?
Post Opinion