I am not staking stratis using raspberry pi yet,but if you would like to start read this article https://stratisplatform.com/2017/03/14/staking-stratis-on-a-raspberry-pi/ and check out the guide here: https://olcko.gitbooks.io/staking-stratis-on-a-raspberry-pi/content/

If you have further questions you might want to check in the stratis slack group. I'm sure there are people who can help you much faster there as you can chat instantly.