I agree with Flyin'Dutch's comments.
TBO-busting is not a sin (see generally
here), and there is a lot to be said for the saying "if it ain't broke, don't fix it". Of course, regular compression checks, oil analysis, etc. would be prudent. And a lot depends upon the particular engine type, and aircraft use (e.g., a O-360 is much more likely to exceed TBO than an AIO-360, especially if the latter is regularlay used for aerobatics).
To the best of my knowledge, Lowtimer is quite correct that an engine operated ~300 hours per years is significantly more likely to exceed TBO than one that is operated, say, ~25 hours annually.
If you are really interested, I strongly recommend obtaining a copy of
Firewall Forward: Maintaining Power (volume 4 in the Light Plane Maintenance Library, ISBN 0-9613139-1-9). Part III of that book (pages 113-15149), entitled "Getting the Most Engine Life", contains two chapters ("Getting to TBO and Beyond" and "Major Overhaul") that are full of useful and reliable information. Additionally, Chapter 3 ("Cold-Weather Safeguards") has good stuff on pre-heating.
Speaking of pre-heaters:
here is a link to a decent little article on AvWeb (and see also the preheat section in
"Yes, it's Winter"). Aviation Consumer's article
"Pad, Plug or Flamethrower?" is also worth reading. Personally, I prefer the flexibility of forced air (something like
this, although you could probably make your own for less money).