1-Asking someone to pour water for one's wudu, with no excuse, because it is a luxury which does not suit the state of worship.

But it is permissible because it was revealed in the Sahih that Username and others (of the companions) poured water for the Prophet (P. B. U. H) to perform wudu

[See Al-Bukhari, Vol. 1, The Book of Wudu, Chapter 34/179-180]

It is permissible to ask someone for help in fetching water.

2- Shaking off the water after wudu because it is improper-like one is ridding oneself of worship.

3- Drying the body parts with a towel except when there is a necessity, as to avoid najasa or in cold or hot weather.

Maymunah (G. p. H) narrated in the book of the description of ghusl from janaba

"The Prophet (P. B. U. H) was brought a towel but he did not touch it".

[Muslim, Vol. 1, The Book of Menses, Chapter 9/38]

Moreover, it (the water) is the trace of wudu so it is better to leave it.

4- Using less than one mudd [Mudd (a volume measure) is a cubical vessel, the length of its side is 9. 2 cm] of water for wudu.

Anas ibn Maiek (G. p. H) narrated that:"The Prophet (P. B. U. H) used to make ghusl with one sa "

[Sa' (a volume measure) equals four mudds] up to five mudds (of water), and perform wudu with one mudd".

[Al-Bukhari, Vol. 1, The Book of Wudu, Chapter 46/198]

5- Talking because it distracts one from making du'a, unless it is necessary such as answering salam which is obligatory while to abandon talking in wudu is sunna, and the obligation is stronger than the sunna.

Therefore, you should not say salam to one who is making wudu until he finishes, so as not to cause him to talk.

6-Slapping one's face with water.