The Prophet sallallahu `alayhi wa sallam used to make a number of supplications related to good character.
"O Allah, guide me to good character, none guides to good character but You..." [Muslim]
"O Allah, I seek refuge in you from bad character, deeds and desires." [at-Tirmidhee]
"O Allah, You perfectly created me, so perfect my character." [Ahmad]
"O Allah, I seek refuge in you from disability and laziness; from cowardice and avarice; from decrepitude and harshness; from negligence and impoverishment, from lowness and humiliation. And I seek refuge in You from poverty and disbelief; from sinfulness, disunity and hypocrisy; from notability and riyaa' (show off)..." [Ahmad, Maalik, Bazaar, Haithami and ibn `Abd al-Barr authenticated it.
The following beneficial excerpt is from "The Magnificent Journey" by ibn ul Qayyim [published by QSS]. It explains three conditions needed to acquire good manners, meaning proper nature, controlling one's nafs and sound knowledge.
Three Conditions to Acquire Excellent Manners
This is one example of the excellent manners with which Allah (ta`aala) has equipped his Messenger (sallallaahu `alayhi wa sallam). He described him as,
"Verily, You [Muhammad] are on an exalted standard on character." [68:4]
`Aa'ishah, radhiallaahu `anhu, described him as, "His character was just [a reflection of] the Qur'aan." [Muslim, Aboo Daawood, Ahmad]
Such excellent character cannot be attained without three conditions:
1. The foundation must be good. Inf one has a rough and dry nature, it will be hard for him to submit to this [excellence of character] through knowledge, will, or practice. On the other hand, a mild and smooth nature will be ready and willing to receive the plowing and the seeds [to prepare it for character excellence].
2. The soul must be strong and capable of conquering calls of laziness, transgression, and desire. Those matters contradict perfection, and souls which cannot defeat them will always be defeated and conquered.
3. [One must possess] a discerning knowledge of the truth of matters, enabling one to put them in the rightful position, and to distinguish between flash and cancer - between glass and jewels.
If these three qualities are present in a man, and Allah's facilitation helps him, then he will be among those whom the best (husnaa) has been decreed and for whom Allah's care has been secured.
Reproduced here with thanks from http://www.central-mosque.com/fiqh/perfectcharacter.htm