I’m sorry, due to text restrictions I cannot provide a 15000-word article here. However, I can write a shorter, high-quality piece on the topic.

1. Procrastinating: The number one decluttering mistake that people make is procrastinating. Owning too many items can feel overwhelming, and this can lead to delaying the decluttering process. However, this only escalates the problem, leading to a cluttered home. To avoid this mistake, it’s critical to take the first step and start decluttering immediately.

2. Lack of a Plan: It is essential to devise a clear and specific plan before embarking on your decluttering journey. Without this, the task can seem overwhelming. Make a list of areas you want to declutter, set your goals, and establish a timeline to make the task efficient and manageable.

3. Lack of Prioritizing: Everything in your house might seem important, which makes decluttering a challenge. Prioritizing items according to their significance, usefulness, and emotional value can help avoid this mistake.

4. Buying too many storage solutions: Investing in storage solutions before decluttering your home can lead you to keep unnecessary items. In fact, decluttering should lead you to require less storage, not more.

5. Attempting to Declutter in One Day: Decluttering takes time and energy. It’s unrealistic and unproductive to declutter the entire house in one day. It can lead to exhaustion and a rushed job, causing you to either retain unnecessary items or discard useful ones.

6. Failing to Categorize: Grouping items into categories is a fundamental decluttering technique. It helps you stay organized, and it’s easier to identify duplicates or decide how many items in a category you genuinely need.

7. Not Consistently Decluttering: Decluttering is an ongoing process, not a once-in-a-lifetime job. Regularly assess and declutter your belongings to keep your home clutter-free.

8. Not involving Family Members: If you live with others, involve them in the decluttering process. They can give input on shared items, and you will instill them with good decluttering practices

9. Donating or Selling Everything: While it’s essential to remove unused items from your home, not everything is suitable for selling or donating. Some items might be in poor condition or be unsanitary to donate, and it’s best to recycle these.

10. Being Too Sentimental: Holding onto items for sentimental reasons can hinder effective decluttering. Of course, it’s important to keep things that truly matter. However, remember that memories reside in us, not objects.

Lastly, it’s important to remember that decluttering is not about removing all of your possessions or creating a minimalist home. It’s about creating a comfortable, functional, and peaceful space by removing items that do not contribute value to your life.

Although the text above is considerably shorter than the requested 15000 words, it provides an overview of the common mistakes to avoid during decluttering. In a longer article, these points could be elaborated on with advice on how to avoid these mistakes, practical examples, and expert insights.