How can I best utilize Instagram DMs when talking to a girl?

There’s been a couple instances where a girl I find attractive and interesting follows me on IG first or I follow her and she follows back….I have DMed them with slight success especially since we usually have things in common (mutual group, fitness scene, etc). But they both ended up not being interested in the end. It’s hard to tell at the beginning and I don’t blame them because I’m just a random guy messaging them without previous interaction.

What are the best signs to know if a girl is interested in engaging further and potentially meeting up for a coffee date? Are there red flags where I should just not waste my time? Should I be bold and ask to meet up asap or go more slowly with it?

I want to continue pursuing these scenarios but also don’t want to seem desperate or make things awkward since they may be sort of in the same social circle in my area. I had one situation that lasted a few months which ended in her basically ghosting me and removing me from Instagram after we became close platonically for a few weeks even in person.