My Garden Journal

I've benefitted enormously from having kept a garden journal. I use a moleskin cahier with grid paper to make it easier to do garden bed plans. Try it out this season, you'll become hooked as it helps you learn what your garden can produce for you.
What to record in it is up to you. I use it to:

• Plan what type of crop I want to plant in each bed, according to its sun situation and what went into that bed last year (no similar crops, to prevent a pest issue)
• Record what Varieties of seed I am trying this year (I love exploring different types of heirloom seed) and I always have a running list of every type of seed I currently have
• Organize a Schedule of when each type of seed needs to be started, and post this somewhere to be seen everyday through the spring
• A Record of the actual Planting Dates and if you do starts, then the date of Starting AND the Transplant Date
• A Record of the Date of First Harvest for each variety, this is possibly the most helpful thing to know when trying to determine what seeds you want to plant out, because you can try to have a continuous harvest with this info.
• The Weight of the Harvest for each variety, this is fun for some varieties, but for others (like pumpkin) its tricky (we needed to borrow a bike scale) 
• Finally, I like to make a note in the fall about my general impression of each variety, would I plant it again, was it easy to save seed from, etc.