First, make a detailed plan of attack. Decide which part of the house to clean first. The 'disaster areas' of a home can vary greatly from person to person or family to family. Determine which room or rooms are the messiest and in the need of the most help first and focus on those. Come up with a plan detailing the tasks needed to clean each room and try to estimate the time needed for accomplishing each task. A time frame is very important because it will help you monitor how long you have spent on a task and be helpful in progressing. It can also be advantageous when you feel overwhelmed with the number of tasks you must do. Focus on the tasks one at a time and as you mark them off your list you will experience a sense of accomplishment that will hopefully keep you motivated to continue.
Next, start immediately with the cleaning phase since this part will eat up majority of your time. Start by organizing your things. Sort out your clutter by grouping everything together into piles or even plastic bins. For example, Clothes with clothes, shoes with shoes, mail with mail, etc. For those things that you still want and can use, leave them are they are. But for those items like clothing that you no longer want because they are out of style or don't fit or you simply don't like them anymore, remove them. You can sell them at a garage sale or a consignment shop, give them to friends or family, or donate the items to the charity of your choice. The specific technique you use to declutter your home can vary greatly. Some plans take months while others can be accomplished in a matter of days.
Sometimes, it may not be possible to reach your decluttering goals in short order but no need to fret. If you find you are becoming discouraged because the job looks too big or seems to be taking too long, take some time off, revise your plans, and try again. Do not stop until you get the desired results. After all, you are the one who is going to live inside your home. You would not want to endure a dirty place everyday for the rest of your life now, would you?