When I first moved here I found trash collection protocol so amusing that I actually wrote a whole essay about it. If you have a maid who is at your house daily from early morning on, you can skip this section. She will take care of the trash and you will never have to think twice about it. For the rest of you, here's the drill.
If you don't already know, ask a neighbor what day(s) and time the trash truck comes to your street. In most neighborhoods the trash is collected anywhere from one to three times a week. Gather up your trash and have it ready to go the night before. On the morning of the designated trash day, start listening for a loud metal clanging sound. That means the truck will either arrive shortly or is
already waiting. Grab your trash and carry it to the truck.
Don't worry about looking presentable. Slippers and bed head are perfectly acceptable. (But not bare feet, which is always a faux pas when in public in Mexico, the beach notwithstanding.) Wait in line politely with your neighbors, and when it's your turn, pitch the bag up to the guy waiting inside the truck. If you are obviously too weak to pitch your bag, someone will help you.
When you get back into your house, note the time. The trash truck will come more or
less about that time of the day on its designated days, except for after holidays, when it tends to arrive later. In some neighbor-hoods, like Guadiana, you can hang your small trash bags on a hook and the trash men will gather them up for you.