As I understand it, the USPTO will not examine the provisional patent until the non-provisional is submitted. Once filed with the USPTO is there any reason not to share the provisional application with the public? Family members? Potential customers?
If you file the same application content of the prov. as a non-provisional, you're fine.
If you add a few improvements, they get the filing date of the non-prov. app.
The non-disclosure of the prov. in combination with the priority protects you against having that prov. used as a basis for obviousness. If however you disclose the prov., your improvements (= anything not disclosed in the prov.) can (and often will) be obvious in light of your disclosure.
(I'm ignoring the grace period, because it's US only.)