Texas hold'em, betting rules of thumb

This isn't a good idea, as any decent observant player will realise pretty quickly what your particular bet sizings mean with regards to your holdings.

Generally in poker it's best to be balanced. When bluffing, we should be doing similar to what we'd do when we're betting for value. As a general rule of thumb raising 3x the BB preflop is a good sizing early on in a tournament. You can make this a bit bigger if people ave limped in before you, so as not to give the limpers too good a price to call.
Later in a tournament, as stacks become shallower, you can make your pre flop raises smaller 2x - 2.5x BB. This is because players don't have a lot of BBs and are less likely to call with rubbish.
As you get deeper in a tournament, stealing blinds and antes becomes very important, so the smaller the raise size you make, the better price you're giving yourself to win the pot. If you're raising to steal blinds a lot at these stages, the smaller pre flop raise size you make, the more money you're saving every time you have to fold to a reraise/shove.

That's good advice, particularly the betting strategy towards the end of the tournament.
I've both won and lost games due to the blinds at the end of the game.