How to prevent blocked bog happening again?

Was surprised how many others suffering from a blocked wc. First time for me, and it wasn't due to objects/materials that shouldn't be there. I found same miracle cure - plastic bag on a mop as plunger - in my DIY book published way back in 2003.

What I now want to know is how to stop it happening again.

The market is flooded (no pun) with products to prevent limescale and odours in our loos. Isn't there a safe product for use at intervals to disperse unseen crud in the S-bend that results in unwanted blockagea? Mr Muscle was mentioned - but only as a no-goer. Any suggestions or better - recommendations anybody ?

Oldbill
January 2010