The cursus honorum officially began with ten years of military duty in the roman cavalry (the equites) or in the staff of a relative or a friend of the family. Nepotism was not seen as a wrong way of achievement: it was an integrated part of the system. These ten years were mandatory for qualification to political offices. In practice, the rule was not adopted so rigidly.
The following steps of the cursus honorum were achieved by direct election every year. In Rome there were no modern-like political parties. Candidates were elected due to family reputation and/or their own. Older families candidates were favoured because they could use their ancestor's feats as electoral propaganda.
The first official post was of quaestor. Minimum age to apply to this election was 30 years. Men of patrician rank could, however, subtract two years to this minimum age, as well as the following. Numbered 8 to 12, the quaestors served in financial administration at Rome or as second in command to governors. After election to quaestor, automatic membership in the Senate.
At 36 years of age, the successful men could try an election for one of the four aedile positions. The aediles carried administrative responsibilities in Rome. This step was optional.
Praetors were elected in a number of six, from men older than 39 years. The main responsibilities were of judicial kind in Rome. They could also control provinces not given to consuls and command one legion.
The consul office is the most prestigious of all and represented the summit of a successful career. Minimum age was 42. The names of the two elected consuls gave the name to the year of the office. Consuls were responsible for the city's political agenda, commanded large-scale armies and controlled important provinces. The attempt for a second mandate as consul could only be submitted to election after an interval of 10 years.
The censor office, the only with a period of five years, instead of the usual two, held little more than representative duties. Censors were responsible, among other things, for the moral status of the city.
To have held each office at the youngest possible age (in suo anno, "in his year") was considered a great political success, since to miss out on a praetorship at 39 meant that one could NOT become consul at 42. Cicero expressed extreme pride both in being a novus homo ("new man") who became consul though none of his ancestors had ever served as a consul, and in having become consul "in his year".