Social media is your friend,take and share images and you might get lucky with a team or sponsor who may provide an event pass for a weekend in return for images. From here hopefully you can progress to working for a team or sponsor on a regular basis and hence get enough published to get the next step up on the ladder.
Its not hard getting accredited but it is hard making any money as everyone actually works for free or very little i find in BSB if thats what you are after doing.
We are actually told at BSB that we cant sell images to the public and can only supply media outlets,riders,teams and sponsors but i can guarantee you will see most selling or promoting selling there images on social media and even some very openly on e-bay, no one seems to care to be honest.