There are many conditions for wudhu, which are described here:
1. The water of Wudhu must be (1) Tahir, (2) Mutlaq and (3) Mubah;
2. The place where Wudhu is being done must be mubah;
3. The pot in which the water of wudhu is kept must be mubah and should not be made of silver or gold;
4. There must be time for wudhu and Salat. It means that if time of Salat is so short that if you begin wudhu, the Salat will not be performed in time, then you should not make wudhu; instead you are required to do tayammum. But if the time needed for tayammum is the same as that of wudhu, then wudhu should be done. .
5. The face, hands, head and feet (which are called Organs of wudhu) must be tahir at the time of wudhu.
6. Wudhu must be performed with the intention of qurbatan ilal-Laah, i.e. to obey the order of God, to become nearer to Allah. If you do wudhu to keep cool or with any other intention the wudhu will be batil (null and void);
7. Tartib should be maintained. It means that you should begin by washing your face, then the right hand from elbow down to the fingers, then the left hand accordingly, then you must do masah of a portion of your head. then the masah of feet. It is better to do the masah of the right foot, then of the left; though masah of both feet may be done together;
8. Muwalat. It means that you must do all the above mentioned works in wudhu without interruption;
9. You must do all the acts of wudhu yourself. It means that if you tell another person to wash your face and hands etc. or to put water upon your face or hands etc. the wudhu will be batil (invalid); but if you are unable to do wudhu yourself (for. reason of illness), you may seek help from others in wudhu.
10. There must not be any difficulty or danger in the use of water
11. There must not be anything on the organs of wudhu which may prevent the water from reaching the organs e.g. ring or oil or nail polish etc.
12. Washing must be done in the proper way. It means that face must be washed beginning from the forehead up to the chin (not in opposite direction), hands must be washed beginning from the elbow and ending up to the tips of fingers (not vice versa).
13. Masah (wiping) must be done from the remaining wetness of the water upon the hands. No other water should be mixed. Remember that if your head or feet are already wet, the masah will be batil, and accordingly wudhu will be wrong. Therefore, your head and feet must be dry before masah.
Some people put some drops of water on head before starting masah. This is absolutely wrong, because their head or hair becomes wet before masah. Likewise, you should remember that while doing masah of head, your hand should not touch your forehead. Otherwise the water of forehead will mix with the water of hand. In that case the masah of foot will become wrong. Some people, after washing the left hand, wipe their right hand again by the left hand in the manner of washing. It is wrong for two reasons:
1. It disturbs the tartib;
2. It puts extra water on the left hand, putting the validity of the masah of the left foot in question.
There are many things mustahab (sunnat) in wudhu, washing the hands twice; gargling three times; rinsing the nose three times, (all these are before wudhu). Washing the face and hands during wudhu twice, etc.