Met her for the first time and don't know how to take things forward.

I been talking to a girl which I met online and we finally decided to meet as I was in the city. Unfortunately, she had a train to catch back to her hometown so we couldn't spent much time together. We just met for half hour in a cafe. The meet was pleasant and we decided to meet again next time she returns that will be some one month after. I kinda like her and I would like to spent some time with her and see if this evolves into marriage. Now we would meet meet after a month. What should I do now so she doesn't forgets me and is still attracted to me. Should I text her often and if so what should we talk about? I'm 26 and this is the first time I'm meeting a women and I don't want to loose the opportunity to make her fall for me. I genuinely wish she reciprocates well. Moreover, she commented I look a little different online 😭😭. Maybe, because I use filtered pics and I'm a little skinny guy but I have an above average face. So I'm planning to join a gym soon. I hope this isn't a deal breaker. I haven't been so underconfident in my life lol. Apart from that I still think she's attracted to me. We flirt a lot over texts and online in comments. Please advise me. Backstory in the comments.