I was sick both pregnancies and the first was the worst. I was sick every five or six minutes, or more often sometimes, I just couldn't leave the loo, all day long. It got a bit better at about 21 weeks (down to about 4 pukes a day) then worse again at 28 weeks and I was retching in the delivery room, and not being allowed fluids because I was having a scheduled c-section.
Things that made it worse: green stuff, vegetables. Hot spicy food was worse to throw up. Cheese the worst.
Things that made it better: constant eating, ice. Ice pops seem to delay the puking, combining the act of eating with a sort of stomach numbing effect. And they replace badly needed water & sugar. Have a huge stash of ice pops, sun lollies, etc.
The main thing that helped: sleep. The reason my sickness started up again badly was I moved to a very different time zone and my sleep went tits up and the ice didn't help any more and I think sleep was the biggest factor. If I got almost no sleep, I couldn't stop throwing up. If I got a lot of sleep, hours would go by with no puking. It's not very easy to get sleep when you're pregnant, sometimes.
Second pregnancy, I took drugs.