Do as I say, not as I do.
Get started early. Even if you feel, as I did, that there is some task you must accomplish before you can be sure of grad school as your path, start early. Get your transcripts in october or november at the absolute latest. Start asking for letters of recommendation before november. Get everything prepared, send it, and check with the school to make sure they got it (that I am doing). Make sure that there is enough time such that if they did not get it all, you have time to get it to them before the deadline. In general, be pro- not re- active. And it doesn’t hurt to prepare everything you can as early as you can.
This is close to beating myself up, but not quite there. I may well apply to grad school in the future, and I hope I remember these suggestions. And the mindset in general.