I feel for you, I've had it terribly and it is so debilitating!
For standard morning sickness eating little and often can really help, things like crackers, even before you get out of bed in the morning. Also staying as hydrated as possible. I find sucking mints helps a bit. Don't worry too much about WHAT you eat, so long as it's something. Get as much rest as you can as tiredness really makes it worse.
If you are finding that you are really struggling to eat at all, are having a hard time holding anything down and are vomiting constantly you likely have something called Hyperemisis Gravidum. I had it with my daughter and the usual tricks won't work for HG, you will need medication. I was on cyclizine from 9-24 weeks with my daughter and have been on it since 7 weeks this time around. It is completely safe to take and really does help. It's really worth speaking to your doctor if you're struggling, even if you don't think it's HG.
Good luck xx