When selling your home, cleaning and decluttering I would say would be the most important things to do. It is easy to lose a purchaser if the house is dirty. Realtors tell their clients to look past the mess, but its tough. It cannot smell terrible either. Smell will turn them right out the door. This also applies to clutter. If you have alot of knick knacks, furniture or just stuff you have collected over the years. Go through it, toss it or pack it up and store it. Sometimes it is worth getting a storage unit if you have no space. You don't want a potential purchaser to think that there is not enough room in your home. You are going to move anyway, so you might as well start going through things. Spend some time on this. It will be worth it!
