I think that pretty much all the things you need to do while pregnant are to look after you. keep yourself well, and baby will be well. so...
rest when you can. You might feel exhausted or your might feel fine. Either way, catching a nap when you can will do you the world of good. And sit down when you can, especially as you grow.
Try to excercise gently throughout your pregnancy, as much as you can, ie if you can only do a small amount, that is fine, but do it. I found i often felt terrible, tired, sick and generally yucky but some fresh air and a stroll or a quick swim did me the world of good, and it helps to prepare for childbirth.
Drink lots of water, as much as you can in the day. This eases any morning sickness (might not stop it but helps a little) and helps with tiredness, reduces swelling (other than a nice bump!) also reduces impact of any stretch marks you might get as it keeps skin supple.
Eat as well as you can, sickness allowing. If you are suffering from MS, take supplements, and iron sachets are good (spatone or similar do not give you constipation). Eat small and often if you need to. Eat whatever you might crave.
Smile lots, laugh lots, be happy lots as this increases seratonin which is great for baby.
Make sure you can rest at work, take all the help you are offered.
Congratulations and good luck x