Scraping paint by hand is a grueling task because you've got to attack it from every direction. But compared to power grinders and sanders, it's the least damaging way to remove the old layers. You can speed up the process by using a heating gun to soften the paint (as shown).
Safety First: Use a respirator when scraping paint by hand. Also, make sure you protect the surrounding work area—including any plants and shrubs—with a tarp covering.