Should I offer a free trial or pay-for-results deal to win agency clients?

Both can work. Trials, risk reversal and performance based arrangements help win clients, because anything that makes signing up no risk or low risk removes a reason to say no.

A performance based offer works best when you are in charge of providing the end result. Many business owners are not good at sales, so if you generate leads or appointments but they do not close them, they may think your system did not work. If you do the whole thing, including closing, or deliver the end result yourself, it can work out well. Tying your success to the client being good at something like closing can cause friction.

An easier, lower risk offer is reputation: guarantee more reviews, take a list of the client's past customers and ask them for reviews, and the client pays only if reviews come in. Then set it up on an ongoing basis. It needs less messaging, and the same automation or agents can serve every niche without customizing each one.