One of the most important parts of brewing is taking good notes. Aside from printing out the recipe you're brewing there are a bunch of other things that you should be writing down, in three months you're probably not going to remember if you were one degree high or low on your mash or how good the crush was on that bag of grain.
I was used to miss some important details when taking notes and I was unhappy with all the spread sheets I was finding online so I decided to make my own note taking sheet.
This is what works for me. The Variables table is for the amount of strike/sparge water as well as the temperature, I use this website to fill out the table, it takes it's calculations from Designing Great Beers by Ray Daniels.
There is a space for your water adjustment information you can note the amounts of chemicals you're adding and the final water profile for that beer. To get this information I use the EZ water calculator V3.0. It can be downloaded as a spreadsheet.
The averages table is something I developed in response to using a RIMS system and having multiple data points for my mash. Home-brew mashtuns are notorious for not holding a uniform temperature throughout so I average 3 of my data points (center grain bed, RIMS output, blichmann thermometer on my mashtun) throughout the mash. I take these average readings and average all of them to get what i call my mash temperature.
The bottom table has a space to keep track of all your cellar activities (racking beer, dry hopping, temperature changes, gravity changes) as well as your attenuation and alcohol by volume. Here I also keep track of my kegging activities (date, C02 pressure applied) and bottling information (date and number of bottles)
Aside from all the tables there is a space to write down your starter information, a space to write the beer you're brewing, the version and the date, and a space to make notes for a starch conversion test.
Usually any other notes I need will be put on the back of the page or on a separate blank page, usually this is where i write information on my flow rates, crush information or anything else that comes to mind. I attach this to the recipe I have formatted in beer alchemy and printed out as well as the receipt from my home brew store giving me a complete picture of the beer.