Vague claims are easy to write and easy to disbelieve; specific claims take more work to craft but are dramatically more persuasive.
Replace Round Numbers With Exact Ones
"$1,847 in extra revenue" reads as more credible than "over $1,800," simply because exact figures feel less like marketing and more like fact.
Name Names Where You Can
Specific customer names, company names, and dates make testimonials and case studies far more believable than anonymous, generic praise.
Trade Adjectives for Evidence
Instead of calling something "amazing" or "revolutionary," describe specifically what it does and let the reader draw that conclusion themselves.
Next step: Use the Sales Letter Writer to tighten a vague draft into more specific, credible copy.