I'm used to playing deep stack tournaments at a local pub game. 150,000.

Which is quite a lot, most other tournaments and casino tournaments are around 20k starting stack.

Meaning you have less chances to make mistakes.

Can anyone give me some useful advice about short stack tournament strategy especially for someone who has been playing since November and has a bad bluff.

You'd have to define the blind structure.... Saying chip amounts is pointless without that.

blinds on the 20k would start at i think 100/200 and go up every 20 minutes.

starting with 100bb is not a quick game
blinds going up 20 minutes is not a quick game

It's going to be a pretty fast structure. At the second blind level, the starting stack is 50bb. I assume they don't have 150-300 because if they're starting with 100-200 the t100 chip is the lowest denomination in play.

we play basically the same structure at our local and it plays fine

Don't disagree with this chap too much ... but ... this is a typical 'quickie' tournament for casinos and poker rooms. Anytime the average stack could be less than 60BB 20 minutes into the tournament is 'quick'. This typically sets up for tournaments that last less than 4 hours (for sure) and quite possibly less than 3 hours. Our poker rooms want these guys back at the cash tables so they can generate more rake.

That being said .. if you can/do/will run deep into tournaments, then you already know how to play with these stacks. You need to look at BB and blind levels and adjust to your 'end game' poker even though you are at the beginning of the tournament.

The 'nice' thing about these tournaments is that you are typically playing at a full table for a longer period of time than with larger tournaments, so you might have a little more room.

Just remember that you will barely get in 2 orbits per level and to maintain your BB status you must double up every level. These keep you sharp for sure IMO. GL