One of the most important pieces of advice related to moving home is to never attempt to do so on your own; you should always get help from family, friends and from professional movers. It is also important to start early and start young.
Spring cleaning can be good preparation for an eventual move, while there is no such thing as being too young to begin sorting out and downsizing your possessions. Sorting out can start behind closed doors. You can sort out and organize the contents of garages, filing cabinets and cupboards.
If you have plenty of time and are not intending to move just yet, you could simply go through one per month until the task has been completed. Think about the possessions that you make use of on a daily basis and will continue to do so after relocation. Write down these possessions and if something does not make it onto the list then put it into a box. If you have not used these items 6 to 12 months later then they are clearly not all that important to you and should be thrown or given away. Get rid of any and all possessions that are doing nothing but take up space, including such items as un-wearable clothing and expired medicines. The simple fact is that the fewer items you have to pack up and move with you, the cheaper the eventual bill from your moving company for the relocation is going to be.