Since you will be working directly with the Sherpa, and since TradeSherpa is not a party of the contract between you and the Sherpa, the Sherpa will in most cases bill you directly.
Sometimes, the Sherpa may ask TradeSherpa to bill you on his or her behalf for convenience purposes. We will proceed accordingly of course.
Regarding payment methods, Sherpas usually request wire transfers or online payments.
Note: If you intend to pay Sherpas using wire transfer, you may find Transfermate useful for international payments. Transfermate, an Ireland-based company awarded by top companies, enables you to make automated international wire transfers using the internet, with better exchange rates and lower bank transfer fees than traditional wire transfer options. The solution is simple for you, and it does not require any legwork from your Sherpa, so we recommend that you check it out.