The second biggest thing you can do is disable Dropbox, if you use it. Man, Dropbox slows down boot on my computers like whoa.
My experience with Dropbox seems to show that the speed of the Internet connection (or reconnection) is what affects Dropbox. Regardless, doesn't Dropbox do its synchronization after it has loaded, which is after startup?
I've timed my startup by tracing and analyzing all my startup apps (of which I have many, for various reasons), and Dropbox consistently uses a lot of CPU time and slows the computer to a crawl as it's getting going...even if there's no file syncing that needs to happen. Simply the process of loading, connecting to the servers, logging in, and so on seems to take some time. (This is on a 2.3 GHz Core i7 Macbook Pro with 16 GB of RAM.)
If I disable Dropbox, startup is noticeably snappier...but I rely on Dropbox for my business, unfortunately.
