Well, the first hurdle would be learning ancient Greek! (Having studied it for 6 years now, I can confirm that would probably be the hardest part...)

After that, you'd need to become well-respected in your field of knowledge and have powerful, literate friends who would be interested in preserving and circulating your ideas through writing. The 'scientific' and 'philosophical' texts that have come down to us have only been preserved for so long because they were actively kept alive by those living at the time, so you'd need to get a pretty large following like Pythagoras or Plato had. Even then, the versions of the texts that exist today differ substantially to the originals since they will have been copied and translated many, many times over the years.

The best way to get your ideas out there would be in a unified, substantial work (or several works), that need to be well-written, well-argued and engaging. There are two ways to go about doing this: either become a beast at writing in beautiful, prosaic Greek (tough stuff) or get a friend to write about your ideas for you (like Plato and Porphyry did for Socrates and Plotinus respectively, who were apparently awful writers). I'd say the second option is safest!

So, in short: be literate, be engaging, and have connections! Oh, and if you ever figure out time travel let me know, I'd love to come with you and help with those translations :P