I would love to read what are the best tricks you learned in your commuting experience.
I would like to propose a format, where we use one comment for each single trick/suggestion, so if you have multiple tricks, post multiple comments. This would allow upvotes to create a ranking of best suggestions
I will start with a couple of tricks from my experience.
You are totally right. Here a picture of a folded cobag. I usually carry one folded in my pannier when I go to work, so I can pick up something quickly while coming back home, if I need it. They can carry 7 kg if I remember correctly, but if it rains, they are not waterproof.