I don't think money is going to be purely effective at that. This is going to be just a piece of it, but I think having your own interests and hobbies that you actively pursue is a good start. Something that you can be passionate about, and show that in conversation. Like for myself, I've gotten into rock climbing, and can get 'excited' about talking about it. Either experiences outdoors, how it feels, how you approach things. Different equipment, different people that you might know through mutual connections, etc. Praising that person that you both know is a nice easy way to boost yourself in her mind. You can talk with girls that also do rock climbing, or with girls that don't - if you see an opportunity. Such as if you ask what they like to do in their free time, show interest in whatever they might be into. Then when then ask back, you got something as well.
Obviously it doesn't have to be rock climbing - it can be whatever that you're into. Preferably something that's not entirely nerdy, like 'I play WoW all the time' or 'I play DnD'. Although some girls will respond to that if they're into that as well! And it doesn't have to be directly the same activity.
Sporty girls like physical activities. Party girls might like the social scene, doing parties angle. School girls may be interested in various research projects. But you can definitely mix and match, you don't have to tailor to each girl specifically. But it helps having similar pursuits as time.
For brainstorming... house flipping is a half-decent one that you can talk about. Although I don't think too many will be able to relate too much to it. Except if they're also into house flipping or something closely related - then they may also get excited and interested in it. Such as building houses. But I don't think too many girls are...
So perhaps some brainstorming on your own interests or things that you could be interested in, but have never tried before. It's best to pick something that's truly interesting to you. It's hard to fake being passionate about something that you're not. 'Yeah I love sailboating!... except I'm kind of meh towards the whole thing'.
This isn't all of what may make someone exciting, but I think it's a key component.
