Rules very from state to state. They usually involve getting a certain number of signatures to be put on the ballot. Then you just need to go around talking to people and getting votes.

That said you might be a little ambitious I think most people start out in some local races city council or mayor before jumping to state senate. Plus city council is usually part time and you can continue working while you feel out if it's really something you want to do.

In the current political system you need to be involved with one of the two major political parties. An independent can be successful but that is a very difficult path.

You need to get involved at the grass roots level with the political party that most matches your personal philosophy. Getting involved at this level will also help you decide if politics are for you.

Start by forming your political beliefs. Do you believe in big government and the nanny-state, or are you more in favor if self reliance, self determination and low taxes. Does government exists to correct everything that's wrong in the word, or are it's roles much more limited to things like maintaining an infrastructure and protecting borders?

First get your face out there, speak on issues in public forums, like city council meetings, town hall meetings. Network with people in current elected positions, reach out to the city/state committee of your party of choice. State Senate may be ambitious, but if you have a strong body of experience in either government or business, and the money to wage a campaign like that, you can do it. Once you have setup somewhat of a network in your town/city, you will need to fundraise, a dinner of some kind where you can both raise some money and get exposure, maybe even press coverage is optimal. Write OpEds in the state daily newspaper and letters to the editor on issues in your community weekly/biweekly/monthly paper as a good free option for sharing your views.

Make sure you know your state/town filing deadlines and requirements (some offices require a petition with x number of signatures for example) make sure you have an operation that can meet those bare minimum requirements by the deadline once your sure what your running for.