The most common mistakes when refinishing wood furniture can be easily prevented. Most mistakes are a result of jumping into the furniture refinishing project too hastily and visualizing the finished project, without paying attention to the steps. I’ve been guilty of doing that myself.

Always remember to protect your skin and eyes. Wear proper gloves when handling paint strippers and refinishing products. Make sure there are no open flames, and have plenty of ventilation.

The failure to read and follow manufacturers' instructions for paints, waxes, varnishes or strippers is one of the most common mistakes. As these substances can vary tremendously in their chemical makeup and can be hazardous if used improperly, besides giving you results that you did not want.

Before refinishing you need to clean the surface thoroughly. That in itself could save you hours of work, as sometimes after cleaning you might find that all a piece needs is just retouching. Thoroughly clean the surface with a wood cleaner or wax remover to see if you can salvage the present finish.

When you have determined that you do need to strip a piece, always remove all the old finish or paint thoroughly. Leaving spots will yield an uneven finish when you finally start finishing it. Apply enough stripper to keep the surface wet, and never work in direct sunlight as you can dry the wood.

If you spread the stripper and let it sit for days, the paint can become hard again. Plan to complete the stripping in one day so you can remove the paint while it is still soft.

When you don’t wait long enough for the stripper to work, you will have to scrape the wood to get the old finsh off. Check to see if it comes off easily before removing it.

Before you begin refinishing, and right after stripping check for any repairs that need to be made to the surface. Do this before sanding and staining. This will assure a better finish.

Before you apply your stain, the surface should be absolutely smooth. Use the right grit of sandpaper for the right job.

When you are applying a stain or paint resist the tendency to glop on too much. It will only create an uneven and unattractive finish. Apply coats, and wait for the first coat to dry before applying the next one. The product you are using comes with instructions for the proper waiting time.

source from: http://furniture.about.com/od/furniturecareandrepair/qt/wmistakes.htm