Use a checklist.
Take copious notes. Write down everything even if you think it's not important.
Don't panic if something unusual happens. There is no step of the process that is so crucial that 5 minutes of pause and calm reflection will ruin your day or your beer. If something goes wrong, just stop and relax for a minute and think about what to do calmly.
Don't drink at all until you're finished. Cleaning equipment when you're half in the bag is not fun and will lead to taking shortcuts.
Make sure everything that touches the chilled wort is sanitized. Again, if something goes wrong, don't panic. One time I knocked an airlock off the counter into my bucket of chilled wort before pitching. I panicked. I dunked my arm in sanitizer and just reached into the wort and grabbed it. If I would have relaxed and thought for a moment, I could have gone and gotten a spoon or something, sanitized it and used it to fish the airlock out. The beer ended up OK but of course I worried about infection the whole time.
Have fun and good luck!