Start off with cereal, then a veggie or fruit. Probly just feed solids once or twice a day until shes 6mos old, at this stage shes still getting most of her nutrients from formula or bf. My dr also reccomended i wait 3-5 dsys before introducing each new food to watch for any allergy symptoms. Also its good to switch back n forth between green (ex peas) and orange (ex carrots) veggies until fruits come into play. It balences out better nutritionally. Keep in mind too that grain changes, ( going from rice to oatmeal etc) can sometimes cause constipation so doing it gradually can help. Hope this helps lol, it wasnt long ago i was asking a ton of questions about this sort of thing...so much to learn being a ftm!
You should start her off one a day, then 2, eventually over a period of time get to 3x a day. It kind of makes sense to start on veggies, but she's going to end up having her favorites in veggies and fruit. My daughter loved the sweet potatoes.