To be successful in project management and life you must be trusting, but also trustworthy. I learned a difficult lesson recently that blind trust can be a flawed strategy.
Always, always remember, trust must first be earned! Trust takes time, effort, and commitment in order to grow and and be sustaining.
We need to be trusting of others, but first we need to ensure our goals are aligned and we take the time to build a meaningful partnership. Don't rush this phase!
You can't build a long lasting relationship without trust, and you can't have a meaningful relationship with petty self-serving people that are only out to serve their own agenda.
Be trusting, but be vigilent. All that glitters is not gold.