To take the name of Allah subhana watala before doing any action.
"Bismillahir-rahmanir-raheem"
1. An action done without Allah subhana watala's glorious name is incomplete, even though it may seem to be complete, it will not have the barakah in it. There are certain things that become haram, if done without taking Allah's name e.g slaughtering an animal. It is not permissible for a Muslim to eat the meat of an animal, which has not been slaughtered with Allah's name.
It is sunnat to Pray "bismillah" before washing each part (a'adha) of the body in wudhu.
2. AFTER WUDHU
"Ashadu-laa-ilaa-ha-ilal-laahu-wahdahu-laashareeka-lahu wa-ashhadu-anna-muhammadan-abduhu-warasoo-luhu"
I testify that there is no god (worthy of worship) but Allah. He is one by himself. There is no partner in Him and i testify that Muhammad (Sallahu alaihi wassalam) is his servant and his messenger.
After that recite the following prayer:
"Allahuma-ajalanee-minat-tawaa-beena-waja-al-nee-minal-muta-tahireen"
O Allah, make me of those who turn to you and repent much and make me of those who stay very clean and very pure.
In this prayer, firstly we ask Allah subhana watala to make us, from those who ask for forgiveness. This will purify our inner self and then we ask to be from those who keep themselves clean and pure from the outside. This dua also shows that it is giving priority to our inner-self and to be pure from the inside is extremely important.
May Allah give us the ability to act upon these prayers Ameen.