We started with rice cereal, but quickly moved on to (store bought) purees after a week. Sources of iron (like meat and iron fortified cereal) are mainly important to start with as baby's iron stores are fairly depleted by 6 months.
Then introduced banana by itself for another 2 weeks.
Then orange/yellow fruits and veggies and moving on to green.
So far she's had applesauce, carrots, sweet potato, squash, pear, and peas. I stopped doing the wait 3 days in between foods thing.
She eats cereal with a few spoons of fruit or veggie mixed in the morning & evenings, and fruit or veggie alone at lunch. She was starting to hate the cereal by itself after she started fruits and veggies until I began mixing it.