One other thing which used to be true, and I think still is.
The 512m allowance that can be used either for a Lindenhome or a plot of mainland can also instead be deducted from a larger plot of land you may purchase. Thus, if you were to purchase a 2048m plot of land, you would pay Tier as thought it were a (2048m-512m) 1536m plot, or a 1024m plot as thought it were a 512m plot.
Note this only subtracts from the area of the plot, not the Tier level, so you will have to see if it would actually drop your Tier payments by using the adjusted plot size against the Tier level, but it is still a nice option if a 512m plot is too small for you.
The other risk that hasn't been mentioned is that you might come to really like the weekly stipend, the Premium sandboxes, content, and occasional benefits so much that you can't face SL without them