Most important of all, listen to your body! Personally I do not understand it when I see advice that 60-70 miles is "close enough" to a full century. There is a world of difference between 60 miles and 100! Last summer I had no problems with metric centuries, but 75 miles was a quite different story. I injured myself before I reached my goal, and that was due to not listening to my body - or understanding what it was trying to tell me.

Plans are good, and the goal of 10% mileage increase per week works well - but it is important to remember the body does reach plateaus when building a strong mileage base. Really listen to your body, rest days are as much a part of training as active riding is. I learned the hard way that the body couldn't care less about that training chart we have so carefully worked out if it doesn't get the right amount of rest, nutrition, and hydration.

You will find your nutrition requirements changing as you ride longer/further, it is a good idea to take more food with you than you think you will need. You won't regret it either way

For long rides I do not take pure water with me, unless I think I might need something to pour over my head to cool me down if riding in the heat of the day. For long rides I have a hydration pack full of Hammer Heed, and a water bottle of Accelerade. For rides <45 miles I will generally just have water with me and Shot Blocks unless it is VERY hot, then I might put Heed in my hydration pack, it depends on where I am riding.

I hope at least some of this is helpful, take what you need and leave the rest