There are literally hundreds of stripping products on the market today. Some work better on certain types of wood. When purchasing a stripping agent, read the label carefully. If you're stripping a chair or other type of furniture that has nooks, crannies and spindles, consider picking up a spray stripper for those areas. Let the stripper do its job.
Impatience usually leads to a bad stripping job.
If the finish isn't coming off easily after applying a stripper, you didn't wait long enough. Apply a second coat and wait. Always use a scraper with rounded edges. Great damage can and will be done to woods with cornered edge scrapers. Always wear gloves.