Start taking your prenates now, get a check up to make sure you're in good health and require no shots or immunizations that you may not be able to get once you're PG, go ahead and plan out an exercise routine first for your TTC time and then lighter exercise for your PG days, kick bad habits like alcohol consumption, cigarette smoking, and/or coffee drinking, start eating healthy and hey, GO MAKE A JOURNAL!!! They're fun! Also, go buy a small notebook and write to your unborn baby every day, even before you conceive them! Tell them all about what you're doing to prepare for him/her! I wrote to each of my boys when I was pregnant with them but I've already started writing to Baby #3 and we won't even be TTC for another 6-12 months (depending on when hubby finally makes up his damn mind).
Hope that was helpful.