Stripping paint is a relatively easy task, as long as you take the time to work out the best method for each particular area. Flat areas of wood can be quickly stripped with a heat gun, whereas detailed areas are best stripped with chemical strippers.
Using a heat gun is ideal for large flat areas of paint, as long as the surface is going to be repainted. Heat guns will leave scorch marks in the wood however careful you are. Getting them out takes a LOT of sanding! You also need to be careful when using a heat gun near glass as it can crack it. Most heat guns come with a heat shield to help protect glass. For the best results, try not to hold the heat in one place for too long. Move the nozzle over a sizable area until the paint begins to bubble. Then scrape that area with a flat bladed scraper.
Chemical Paint Stripper
If you have a surface with a lot of small detail, it is best to use a Chemical Paint Stripper. You can use a small brush (an old toothbrush is perfect) to work the paint stripper into all the nooks and crannies. Wait for the paint to bubble or blister and scrape off. Paint Stripper is also great for stripping paint off of metal, as metal will conduct heat from a gun as fast as you can apply it. Be careful to follow the manufacturers instructions carefully and only use in a well-ventilated area.
Gel/Paste Paint Stripper
You can buy gel or paste paint stripper as an alternative to standard paint stripper. This is great for stripping vertical surfaces. Again, be sure to follow the instructions carefully.
Any sort of paint stripping can be dangerous. Heat guns can cause very nasty burns in an instant (both to you and to carpets, etc) and paint stripper can cause equally painful injuries is splashed onto skin/eyes. The golden rule: Follow manufacturers instructions to the letter and take care when working.
Neutralising Paint Stripper
Most paint stripper needs to be neutralised if the area is to be repainted. The method varies depending on the type of stripper used, but usually involves washing the area down with water or white spirit.
Once you are happy that the old paint has been removed, sand the surface down with fine sandpaper; fill any holes or dents with the appropriate Wood Filler (or Wood Stopping if you plan to varnish) and you are ready to repaint.
Warning! Lead-based Paint
If the paint you are taking off is old, it is quite likely it is lead-based. This is not very nice stuff and the fumes and dust can cause medical problems. If you think the paint you are stripping is lead based, use a chemical stripper rather than a heat gun, and make sure you dispose of the scrapings safely. Wash your hands thoroughly afterwards.