I think my sticking points mainly reside with...
I'm giving some of these with the assumption that you've got some time to spend with the girl (at least 15 - 20 minutes).
You mean sincerely? You have to have a sincere interest in getting to know a specific girl, or girls in general. It's hard to fake this, so you have to really know what you want from girls.
Knowing what to actually talk about
Getting harder here. It's best if you can find common threads. Ask her about herself - see if anything resonates with you. Find things you'll both find interesting to talk about. Worst case... if you have nothing to go on ... start with the basics (where's she from, what does she do, where does she see herself in the future, etc.) and go from there. Ultimately, being a well read and worldly individual is going to be a massive asset here.
and showing that i'm sexually interested.
If you get any indicators of interest from her (do a search for more or less obvious ones - tons of stuff you can find on Google) - then start by giving her some sincere and specific compliments. Talk about her legs, the shape of her butt and why you like them/it, etc. If you like her smile or eyes, tell her that and use some strong adjectives to describe why.
generating attraction in conversation,
This is the hardest one and there's a number of options here. You can show her that you can have a level headed conversation with her about something she understands or cares about. Don't be afraid to challenge her and her beliefs in a positive way. Also, you can impress her with sophisticated banter or teasing, once you get to know what kind of humor she likes and her personality. Being bold and maintaining a level headed / intelligent, fun conversation, in a nutshell. Again, it helps to be well read and worldly for this, and there's entire books written on banter, humor, etc.