To build trust with anyone you have to make them feel they can trust you. Saying “you can trust me” doesn’t build trust.

How does a brand get you to buy their product regularly? They’re consistent. Take a major coffee chain for example. They use the same ingredients, same materials and follow the same processes. So you know that the outcome should be consistent whether you have a coffee in London or Sydney.

• Add x beans
• Grind beans to y 
• Add z amount of ground coffee to hot water
• Add c amount of milk

There is the idiom, the proof is in the pudding. 

“I can’t believe what you say, because I see what you do.” – James Baldwin

If you want to build trust with anyone; friends, family, partners, colleagues, employees – be consistent. Follow the same actions and deliver the same outcomes consistently.