Firstly it is important that you have all the right gear before you begin the process so check you have the following:
Plastic Mallet (rubber mallet)
Small regular screwdriver
A truing tool is an extra cost, but it ill make life a lot easier in regards to seeing where you need to apply tension on the nipples. An alternative is to turn the bike upside down and use the forks as the tool and the brake pads as indicators to the wheels straightness.
The right components
Weight is an important part of road biking and the choice of parts and frame etc. With a wheel the starting part is the hub in the centre of the wheel. The general rule of thumb is to have a 32 spoke hub, but some heavier riders will need more than this. Conversely lighter riders may want less spokes to save weight, there are a number of spoke designs that keep rigidity but have less spoke, which means less weight and therefore less drag. The rim that you choose is critical as it is the main part of the wheel and its important to buy the right one for your weight and type of riding. Mavic as a brand are good in regards to making rims. DT stainless steel spokes and nipples are the best for beginners and in regards to length there are a number of tools of the web for calculating spoke length. Remember that front and rear wheels require slightly different length spokes as the hubs are different, taking into consideration the cassette.
Lacing the spokes
Place rim flat and insert spoke into hub flange, insert other end into rim and tighten nipple with 4 turns. (Remember to grease the nipples) Install in exactly same way on every other hole the next 7 spokes. Place them in every 5th rim hole. Twist the hub until all spoke are tight. Then place the next 8 spokes through the hub going from the inside out. Make sure you get the same twist on each spoke so everything is perfectly aligned. This should mean you have completed one side. Then turn it over and tap gently in the middle to bend the spokes outwards and find the new resting position. Do the same process as you did on the first side. Start opposite the first spoke you did last time, mark it so you know which one it is.
Tightening and Truing
Sit the wheel into the truing tool. It should be loose but in the effect final shape. The next stage takes a keen eye and patience. Only tighten in less that half rotations as that can make a big difference to the tension. Keep spinning the wheel and applying pressure on either side to get everything to sit in the right place as you tighten it all up.
4 Tips That Will Help
1. Lubricate the spoke nipples, when dry you can tighten them and they feel tight but actually they aren't and will come loose in time and make truing very difficult in the future.
2. Seating the spokes will eliminate any slack, so lie them as flat as you can. If this isn't completed you will find as you ride that the spokes will straighten and loosen, eventually leading to total collapse.
3. Slowly true round and centre the rim, do not do any section up to tightly. It's better to slowly go round and tighten with half a twist. Once you feel the rim is true and semi tight, begin the final tightening process.
4. Apply some pressure to both sides of the rim and in turn the spokes, this will help seat the nipples in the right place before the final tighten.