Judaism is a branch of a larger faith; which I refer to as Semitic Monotheism. There are 3 covenants within Semitic Monotheism. One for the nations (the Noahide covenant) one for the descendants of Abraham, and one for the Jews.
The rabbis are guardians and teachers of all 3 covenants.
One does not need to be Jewish in order to be righteous, or connect with God.
A rabbi will encourage you to connect with God through the Noahide covenant, rather than the Jewish covenant.
You don't have to undergo any particular conversion process to worship as a Noahide.
However, if you feel especially drawn to the covenant of the Jews, and wish to bind yourself to it, you may do so.
A rabbi won't agree to prepare you for conversion if you know little about the faith, or if you aren't even sure you want to commit.
Synagogues are open to anybody, so you can attend synagogue, and learn about Judaism by spending time amongst your local Jewish community.
When you have learned more about Judaism, and experienced it first hand, then you will be better informed about whether you wish to convert or not.
You can continue attending synagogue, even if you don't convert as a Jew.