A few experiences have taught me a lot about touring.
1. The first time I did an overnight by bike, I took an old pup tent from home. I also had borrowed a frame bag from a friend and I had a tool pouch under the seat and a small handlebar bag and a sleeping bag. That's all. In the evening, more than 100 kilometres from home, when I got ready to set up the tent, I realized I had no tent pegs. Fortunately, the ground was quite soft and I was able to find twigs to use instead of tent pegs. Everything worked out. However, I now make sure everything is in proper working order before I leave.
2. A few years ago, coming out of Osoyoos, B.C. and up Anarchist Mountain, I ran out of water in 40 C heat. That was not fun. In a dry climate, you might not realize you're hot and thirsty until it's too late. In hot and dry areas, if there's a mountain pass, it's a good idea to start early in the morning and reach the summit before it gets too warm.
3. For a one-week trip, build in at least one extra day. If something should go wrong and you're stuck for a day, you'll still be able to finish in time. And if it looks as if everything's on schedule, you end up with an extra day for a bit of sightseeing and relaxation. Also, build enough flexibility into the plans to allow some changes. On a one-week tour, I reached one town and was ready to go farther, but I then realized I didn't want to be in that area. It had too many memories I wasn't ready to face. So I turned around and went back on a slightly different route. It was wonderful.
4. While people talk about having too much stuff, it's better to be prepared for the freak weather conditions than to be stranded and unprepared. This is especially true in mountain areas where it's possible to have snow at any time of the year, or in areas where storms can bring cold rain. At the same time, there are all sorts of ways to trim down the weight, without making serious sacrifices
5. Take a notebook and a pen. Keep detailed notes of where you went, what you saw and what happened, whether good or bad. Keep a record of each day's time and distance. At the end of each tour, analyze what happened. Consider what you would do differently, what you would take or leave behind, how you would cope with the things that went wrong. Not only will these notes be useful for a journal; they will also help you make decisions for the next tour. I've kept detailed notes on every tour I've done since 2004 (and I probably have some notes from the last tour before that, in 1992.) Those notebooks are more valuable to me than the pictures I've taken along the way.