First rule about wood and cooking is don't use the wood from trees that have needles (evergreens) unless you think food that tastes like turpentine will be a winner at your next cook out.
Soaking wood in water to make it last longer is, in my opinion, a mistake. Here's why. In order for the wood to reach its kindling temperature, it will first have to dry out or get rid of the moisture. This drying out process causes incomplete combustion. Incomplete combustion causes "SOOT". The only people that like Soot are the chimney sweeps. If you want to make the wood burn slower, try this. Roll the wood up in heavy duty aluminum foil leaving the ends open.
Another thing to consider is wood that is cut to a uniform size will give predictable results in the way of burn temperature and time. The champs at the barbecuing contest always have their wood cut to a uniform size.
Charcoal is a good fuel to maintain temperature with since it has no taste. Keep this in mind. That charcoal cube, is made of burned wood dust. It's held in shape by adding fillers and binders. Glue. Always make sure the charcoal is gray and completely burning before exposing the food to it.
The basic idea behind using the smoke from wood to flavor your food is to get just the right amount of smoke into the food without overdoing it. Experts have determined that the proper amount of time in the smoke is the time it takes to produce about a 1/4" red smoke ring around the meat that will show when you cut a slice off the meat. I recommend one hour in the smoke per one inch thickness of the meat to start. This means if you have, say a ten pound roast that's an average of four inches thick, keep the bar-b-q smoking for about four hours. Finish the cooking with a fuel that is taste neutral like a good charcoal.
Keep in mind, smoke will cause meat to turn red. This will be most noticeable with white meats like pork, chicken and fish. I mention this because, even though the chicken or pork roast you just finished is done to perfection, some of your guests that notice the red color might need some extra convincing.
MESQUITE Strong Sweet taste.
Mesquite is a very hard or dense wood. This translates into a lot of energy in the way of B.T.U.'s. being stored in each piece. Because it is so dense, Mesquite burns very hot. All other things being equal, compared to other forms of solid fuels such as charcoal, hickory or similar hard woods, mesquite puts out about 25% more heat. This wood is a good choice for flat foods that cook quickly like steaks, hamburgers and chops. Because it burns so hot, it will seal the meats flavor; and because it has a very strong flavor, it will be very effective in the short time the meat will be over the fire and in the smoke. If you choose mesquite to flavor a cut of meat that needs to be cooked more slowly, like a roast, keep in mind it won't take long to get all the flavor you want.
HICKORY: Strong taste: Beef, Pork, Fish and Shrimp.
APPLEWOOD: Subtle taste: Ham, Pork chops, Quail.
CHERRY WOOD: Sweet taste: Lamb, Duck, Pheasant, Deer.
MAPLE WOOD: Subtly sweet taste: Turkey, Ham, Salmon, Bass, Bacon.
ALDER WOOD: An interesting wood for a light smoke taste. Particularly good with fish and Pork loin. The pork shoulder is to greasy and will cover the taste. This wood is used to give a really pretty rose coloring to the meat.