The requirements to become a Rabbi vary quite dramatically between the various Orthodox movements and between various Yeshivahs within the movements.
For example- at Yeshivah Gedolah in Johannesburg which is an Orthodox Yeshivah under Minhag Ashkenaz the course is seven years. Most Yeshivahs are shorter than that.
If you are in the US and want to study- probably your best option is yeshivah university. you would do a full yeshivah class load in the undergraduate programme and can do the smichah programme after that. It is a smichah that is accepted by the RCA as a valid orthodox one.
On that note- beware programmes that are not recignised by RCA- this indicates that the programme is not an acceptable one from an Orthodos POV (and yep, I am specifically referring to the smichah given out by the yeshivah of R' Avi Weiss- the smichah is not accepted by the RCa and the vast majority of Orthodox communities and the entire movement is on the verge of being regarded as Conservative).
If you are currently Conservative, you have one other issue that may well need to be resolve- if you are halachicly Jewish. Unfortunately many conservative families have converts in them, and if this is in the martilineal line, it could be a halachic problem. So your first step would be approaching an Orthodox authority, establishing you are Jewish and then starting to study in a Yeshivah or other institution.
On the positive side- I have a friend who was comletely anti-religion, was a punk rocker and as far removed from Judaism as could be imagined. Yet today he is a Rabbi and completing the Dayanut course (the course to be a judge on a Rabbinical court- a further seven years after initial qualification as a Rabbi)