When to Post
You want to post right before most users start to check deals. Thus the best time to post is really between 8-10am and noonish ET, when office PCs start to wake up, self-employed start to go online, stay-home care-givers finish dropping kids at schools, lunch break, etc.
I cannot imagine too many people will check for bargains during summer weekends, in the afternoon rush hours, evening dinner times, and so on. Therefore I seldom bother to post during the evenings or weekends (slow but free home internet access is another reason), and just enjoy other facets of life. The exception is for folks on the West Coast
What to Post
Find your niche if you can, e.g. Butcherboy on guns and farside on freebie magazines. That, however, is difficult for most people (including me). I list the following “safe bet” categories with examples and explanations.