I don't have enough quality contacts to find these clients. And this kind of work is not common where I live so I don't have conferences to go... Do you have any suggestions?
Even on upwork or similar sites, especially when the client is new to site, in case they provided contact info - contact them directly. Yes, and needless to mention - double (better triple) your rate.
For short-term quick jobs - daily (better weekly) charging is preferable.
For long-term-like-regular-job - I prefer hourly billing, because I usually work part-time and with a hourly setup I have a freedom.