When I used to play tournaments regularly I loved re-buys. One of my biggest online cashes was in a $5.50 re-buy at PokerStars
- it was for $5-6k - can't remember the exact amount.
Always enter a re-buy knowing that you will probably need to re-buy at least twice and make the add-on. However there is nothing wrong with giving up if a few re-buys doesn't work. Don't break the bank trying to stay in.
Players will play very loosely in re-buys in the early stages. Take advantage of that by trying to trap them with premium hands. You will need to build a nice stack to stay in.
Always take the add-on - you don't want other players on the table to have a huge chip advantage over you.
Once the re-buy period is over and add-ons are done play will become a bit more normal so pay attention to how other players change up their game at this point.