"The compleat guide to pretentious, unread posts--a new way to be able to post everything publicly without fear of being read"
First of all, put an astrological reference in the middle of a post about "indescrible vision". Write about late night air flights. Write a sentence which says "the problem arises with paradigm". By all means, write bad poetry. Lots of it. Ponder metaphysically about herons and George Harrison while recounting nature walks. Profoundly hurtle your bicycle down a tall hill. Be sure to write about your ponderous theories about the music business. In general, get lost in the "details, details, details".
Don't neglect the classics: San Francisco Thai girl groups; and Uriah Heep; also, try off-the-cuff politics if you value your unread state of privacy; never forget the value of ponderous discussions of music as sound. Be sure you write densely packed bursts of allusions, without splitting them into paragraphs.
Still stumped on how to do it? try a rave review of a Barry Manilow concert or, if all else fails, just cursorily point out the trivia with which you fill your day. Soon you'll get the hang of it, and you won't have to make your posts friends-only.