You haven't mentioned  the State that you want to apply for. So it totally depends on what State you want to apply and if you want to apply under All India Quota or State Quota. State Quota has higher cut off marks. Neverthless, anything less than 550 in General is less. For Tamilnadu, it should be atleast 625. But for Himachal Pradesh it is around 300. For Karnataka, the highest cut off was 512. And you cannot be eligible for State Quota of every State which means you should also try for All India Quota. But without having an idea of which State and Category you belong to, it is difficult to guess your chances. But in general 515 is a score that can give you the best colleges. You have fair chances in states like Maharashtra, UP if you have their State domicile. 

As per your marks theres a good chacch for you to get a seet in government collage

For college refer this

https://medicine.careers360.com/articles/neet-college-predictor