How do I stop my hair from being greasy?

I have thin hair that gets greasy quite quickly, so I have to wash it every morning or it looks horrible. I'm going camping over half term and there aren't any showers there so I can't wash my hair. I've tried dry shampoo and it didn't work, so I was wondering, are there any other ways I can stop my hair from looking greasy and lanky? Also, I need to pack soon so I don't have enough time to buy anything so natural ways would be great, thanks. Thank you in advance for answering. :)