People usually assess the value of someone or something, based on their expectation.
Both a $5 product and a $1,000 product can get a 5 star review.
It is just a matter of what people's expectations are for it.
Set lower expectations - or at least expectations you are sure to be able to fulfill - and do your best to exceed them.
Works with time:
Say you'll deliver something on Wednesday, deliver Tuesday.
Your recipient will be happy.
Generally speaking, delivering your work at, or before time, consistently, will make people happy about working with you. They will trust you.
This matters especially when what you are delivering is part of a process.
If your boss needs to report back to the CEO, following receiving your own report, delivering it before the deadline ensures your boss has plenty of time to do her work.
Works (especially) with results:
Say you'll deliver 100, deliver 110.
Your boss (or investors) will be happy.
In #Sales especially, but in business in general (think stock market reaction to results announcements), delivering on or above expectations is a critical factor in people's assessment of you, and the trust that is put in you - thus in your value.
Underpromise, overdeliver - always.