Great question!
Consultants/experts should be prepared to share the tangible results they've delivered to their clients, whether it's time savings, new revenue unlocked, or another way that your services have helped move the needle for your clients. I came across a marketing agency that does this in a fantastic way right on their website recently:
https://www.lean-labs.com/
Client trust is paramount, and data/results is a crystal clear way to articulate that you have it. Bonus points if your services already leverage your partner's technology/product, because that then opens up an opportunity to be spotlighted in a success story or other co-marketing opportunities.