[prokes]

One suggestion is to throw them hourly work until you demonstrate a good fit. For example, agree to X hours at $Y over a certain time frame. Start off slow before committing. You don't want to deal with the overhead of hiring and firing someone until you are confident it will work out.

And yes, you should definitely take a cut of their time. If you are managing the delivery to client (quality) you can continue billing the client at your rate, while paying junior at a lesser rate. You have found all the work, managed the billing, done the hard stuff and handed it to junior on a plate. Depending on their level, I would say you taking 20-50% per hour is reasonable. Otherwise, why bother?