In your post editing window, you have an options box on the top right corner called "Publish".
Besides changing the post "status" to "pending review" or "draft," did you also try to play with the "visibility" option? Setting that option to "private" should prevent your users from actually seeing the new edits until you set its visibility back to "public."
Also, if you are planning on implementing a post reviewing system in the future, I recommend you made it run in the backstage by always saving your posts as drafts, and then add your reviewers as "users" of your blog so that they can log in and do their edits.
If you don't wish your users to have the same rights and permissions as you do as the creator or administrator of the blog, I recommend that you use a role/capabilities manager to assign users different rights and permissions. I use Role Manager and I'm very happy with it, but there are many options out there to chose from.
Hope this helps. Good luck!