I would concur with all of this advice, and, in particular, the points Kowboy makes about the difference in field sizes between the $5 or 10 events and the $20 and up ones. I would also add that at the lower buy in events you get at least a third of the field composed of maniacs, who are determined to either double up or go broke in the first 30 mins. So the best strategy in my view at the early stages of the smaller buy in multis is to wait for a monster, and otherwise let the monkeys chuck bananas at each other. On the party 5 multis it is not uncommon to lose half the 1500+ field within the first half hour.
One thing to add to Kowboys list of requisite attributes for success, which is partially covered by his second point, but which I believe needs to be specifically emphasised, especially as it has a distinct pertinence in the smaller buy in events: focus. You can get the lucky breaks you need in an event, avoid the bad beats, win your occassional 50/50 race, be playing the greatest poker of your life, but if you lose focus for 10 seconds in a NL tourney you could/should lose all of your chips. In my view, this is the sole most important attribute in online tourneys at the smaller levels, and what will give you the edge over everyone else- I can assure you that almost none of them will be concentrating as hard as you will. It is also very hard to do, especially when you have only paid 5 bucks to enter an event- the tendency is to think 'why bother'?
If you can focus on the game for the entire event, this will be what distinguishes yours results from the average punter.