Packing procedure depends on the duration of your trip. But these are some tips that work regardless of the length of the trip.
The real packing happens as a list, either digitally or on paper. This is where all the important decisions are made. The physical packing is just a realization of the prepared list.
Ideally, you would already have a list of items that should be considered for each trip. Feel free to use this excerpt of my own list as a starting point.
However, each trip typically needs some items specifically for this trip. I have a method for coming up with that list: in the days leading up to the trip, I always keep a little paper notebook and pencil in my pocket. Whenever I think of something that I might need on the trip, I immediately write it down. If I don't write it immediately, I might forget in a minute. This way, I collect my thoughts from a wide range of mindsets, hopefully covering everything I might need. But of course, when traveling, you should not take absolutely everything you *might* need, but only items that you *will actually* need. So this list needs to get filtered later.
While you're at it, you can also make a list of all tasks that need to be completed before the start of the trip. And a list of things that should be done during the trip.
A day before the trip (or multiple days before, if it's a long trip) you should reserve a spot in your room and start making a pile of all the items from the list. The list will help you keep track of what is still missing in the pile.
Once the pile is complete, pack it into your bag and suitcase, starting with less fragile items at the bottom, and the most fragile ones on top. If you're traveling by plane, pay attention to which items are allowed in the cabin and which are allowed in the checked-in luggage.