The most important thing for a trek is to have good boots. It is essential that they remain comfortable and we are used to them, but also that they have a good sole: that they have good grip and are non-slip. If we are in mountain terrain, it is also important that it be relatively rigid. It is also important to consider that they protect the ankle, so you have to consider medium or high cane shoes.
Regarding clothing, we should prefer those made of materials that do not retain moisture. So everything that is cotton should be left at home or to change when we return. For the rest, we will prioritize that they cover most of the body. Of course, always consider some warm clothing and a windbreaker.
A backpack of a size that allows us to carry all our things inside it. Along with it, a bottle to carry our water.
Depending on the season and conditions, we can also consider gaiters.
Trekking poles are always recommended!