One thing you have to know about moving is that it will take time, regardless of how simple or complex you feel your move will be. You are literally taking everything that you own out of your current space and are loading it onto pods or a moving truck, and then you are unloading or having long distance movers unload everything in your possession into your new place. No matter how many rooms it takes to fill up your stuff, this is a significant undertaking. So treat it that way, only make sure you keep your head on straight as you go through this process. It will take a lot of time, but with some careful evaluation and planning of everything you need to do in the months, weeks, days and hours leading up to your move, everything will go smoothly.
Thus, the preparation has to begin once you have finalized that you will in fact be moving elsewhere. It matters not one bit whether your move will be across the town you already reside in or on the other side of the country. The same measures still have to be taken, since this undertaking requires careful planning and a lot of patience too. So when you have confirmation that a move is forthcoming, look into movers. Unless you have just one room to move and feel strong enough to take this on yourself, professionals are ideal here. They ensure your stuff stays intact and that it gets transferred in a professional manner.
Once a mover is selected, the time comes to start evaluating your rooms. If you reside in a single family home that is quite sizable, going through one room at a time is ideal. Start with the rooms that you rarely use or that are for guests. Then work your way through, packing up boxes as you go, until you get to the rooms that are used all of the time. These rooms may get packed up much more slowly, but this is fine. You can leave them for the remaining weeks of you living where you live, but you certainly can get paintings off the walls and home decor items safely packed away. Your last steps in the moving process are to shut down your utilities and services locally and to start them up on or around your scheduled moving date. This is a delicate balance too, since you want to leave enough time on either end to not feel like you are living in the dark ages.