1- Conveying earth up to the part (face and arms) to be wiped, simultaneously with the intention (the intention to convey earth with the intention to perform tayamum).
Hence, it is not valid to face the wind and be content with what the wind blows onto one's face or arms.
However, it is valid to move up earth from your face with the intention of conveying it and then wipe your face with it coupled with the intention of tayamum.
Similarly, it is valid to convey earth up from one of your hands.
2- The intention. It is not sufficient to intend to lift minor or major hadath, or to intend the purification from the state of one of them, because tayamum does not lift hadath.
It is not sufficient to intend (to perform) the obligation of tayamum, the obligation of purification, or obligatory tayamum because tayamum, unlike wudu, is not an aim in itself, but is performed out of necessity.
Therefore, it is not recommended to re-new tayamum, unlike wudu.
The form of the intention of tayamum can be one of the following:
-a- "I intend to perform tayamum to permit the obligatory prayer (or tawaf, or Friday khutba...)."
With this intention you can make one obligatory prayer as well as the non-obligatory (nafl) prayers before and after it; during the particular prayer's time or after it, because nafl prayers are dependent on obligatory prayers.
Hence, if your purification for that which is primary is valid then it is also valid for that which is secondary [Hence, if you forget one prayer out of the five prayers of one day and night and you cannot remember which one it was, then you should make up for five prayers with one tayamum, because the missed prayer is only one and the others are not obligatory.
If you perform an obligatory prayer on your own with tayamum and then find a congregation and want to re-perform the prayer with that tayamum, you should regard the first as the obligatory prayer (and the second as sunna)].
With this intention as well, you can legitimize performing funeral (janaza) prayer, the prostration of thanks or Quran recital, touching the Mushaf, and having intercourse after menstruation. (pa: 78)
-b- "I intend to perform tayamum to permit performing nafl prayer (or nafl tawaf)".
With this intention you are permitted more than one nafl, intercourse after menstruation, but no obligatory prayer.
If you intend permission to perform prayer without specifying whether it is obligatory or nafl, then this will cover nafl prayer only.
-c- "I intend to perform tayamum to permit the prostration of thanks (or Quran recital, touching the Mushaf, or intercourse after menstruation)".
With this intention you are not permitted any prayer, be it obligatory or nafl.
-d- "I intend to perform tayamum in place of the obligation of ghusl to permit the obligation of prayer".
With this intention you are permitted prayer, reading the Quran, staying in the mosque and other things which are permitted in ghusl.
If you make minor hadath afterwards you can make one of the above mentioned three forms of intention as necessary.
It must be noted that one's intention must be coupled with conveying earth and continue until one wipes part of the face.
Hence, if you make minor hadath after conveying earth and before starting to wipe your face, you should not use this earth but start all over.
3- Wiping the face and arms including the elbows for Allah (G. B. H) says: {And you find no water, then take for yourselves pure earth and wipe therewith your faces and arms} [Al-Ma'idah: 6]
The evidence that the part of the arms that should be wiped includes the elbows was mentioned by Al-Shafi'i in a statement which means that Allah (G. B. H) orders purification of the four limbs at the beginning of the above mentioned verse then he counts out two of them at the end of the verse.
Hence, the limits of the two limbs (arms)of tayamum remain as they are in wudu because if they were different Allah (G. B. H) would have indicated that Muslims have agreed that the face and arms are included in tayamum just like wudu.
It is not compulsory to get earth to the roots of the hair.
It is not even recommended to do so because, in contrast to water, this is quite difficult.
However, one should pay attention to facial wrinkles and folds, such as the inner and outer corners of the eyes, and underneath the protruding part of the nose because all of these are parts of the face.
Many people do not follow this.
One should not forget to take care of the visible part of the lips when closed.
4- Striking the ground twice [Al-Nawawi said: "This is common in the Shafi'i school, and it has been revealed that Al-Rafi'i has authenticated it as a recommended rather than obligatory act". Al-Majmu', Vol. 2, page 254] , one for the face and the other for the arms.
Ibn Umar (G. p. H) narrated that the Prophet (P. B. U. H) said:
"Tayamum is two strikes one for the face and the other for the arms to the elbows".
[Al-Darqutni, Vol. 1, page 180]
5- To do the two wipes in order.
Hence one should wipe his face before wiping his arms (whether tayamum is from minor or major hadath), just like wudu, because in tayamum they are two parts.
The evidence for order is what Allah (G. B. H) says:
{And rub therewith your faces and arms}.
The 'and' according to Al-Shafi'i is to indicate a prescribed order as we mentioned in wudu.
If one abandons the prescribed order then tayamum is not valid with regards to the arms, however it is still valid with regards to the face, hence one must redo the arms only. (pa: 79)
It is not necessary to follow order when taking earth for the face and hands.
Hence, it is valid to strike the earth with your hands once and then wipe your face with your right hand and wipe your right hand with your left hand.
However, it is necessary to strike the earth again to wipe your left hand.