Many homes feature a wood porch area at the front door, and on older homes it is usually covered in many layers of paint from years of maintenance. It takes certain methods to do a good job of porch painting, and you must treat and prepare the old paint well if you want a long lasting and appealing finish.
Most porches can be divided into four main components: the deck and steps, the railing and spindles, the posts or columns, and the overhang (which includes the ceiling and rest of the trim). Chances are the current paint is an oil-based product. This is likely just based on the age and how long its been since the porch was last painted. Another clue is that oil for floors is quite glossy, and it has a hard and smooth finish.
A porch needs to be clean to be re-painted, so it is advisable to power-wash, rather than clean by hand. This will be great for getting dirt out of the cracks between floor-boards, and also remove some of the loose paint.
The deck gets the most traffic so we want to prepare it well. The most important step is to scrape and scuff sand to remove any loose paint and get rid of the gloss. If you sand well, you may not need to prime depending on the floor paint you purchase, as many are self-priming. You want a dull, rough surface for the paint to "bite" into. You must also thoroughly clean and remove all sanding dust prior to painting the finish coat.
The railroads and spindles will follow the same guidelines, but these are hard to scrape and sand, due to their shape and complexity. You need to devote extra time here and remove all the loose paint. Once that is done, a great tip is to fill gouges and depressions with a premium filling compound. This will conceal the uneven texture where paint was scraped off. Allow the filler to dry, then sand flush with the existing surface, and prime to seal the compound before painting.
Posts are a focal point so they should also be well prepared and filled to achieve an even finish. You can make good use of caulking by filling all cracks in the trim. Caulking can vastly improve the look of a painted beadboard ceiling by filling all the cracks. The caulking can be painted over directly after a few hours of drying.
It is important to paint your porch in the right order as well. Always work top to bottom and paint the upper areas completely before starting the deck and steps, so you do not need to walk on them. Make sure to allow a good 24 hours of dry time before foot traffic.
Many paint manufacturers have a water-based "Porch and Floor" product which is designed for porch decks and can be used for the rest of the porch as well. Since oil paints are being phased out this is the best option, and will be easy to re-coat in the future. Remember that prep is the most important step in any painting project. Porches get a lot of wear and tear, so its all the more important to do it well.