I introduced my DS to solids at six months. I did not give him rice cereal because my ND said that infants lack the digestive enzyme to breakdown the rice and therefore end up getting constipated. When I did finally introduce grain it was at nine months and it was oatmeal. Ds loved it and it is such a great way to start the day. He is 28 months and still starts off with a bowl of oatmeal everyday. The great thing about the oatmeal (or really any other single grain like ground brown rice) you can "hide" some nutritious foods like broccoli or in out case fish oil in it with fruit puree and he loved it.
To the pp, I avoided carrots until he was seven months old cause of the whole nitrate business. The book Super Baby Foods also recommends waiting until atleast 7 months old.
As far as greens go between 6-9 months we did broccoli at 8 months, green peas at months and green beans at nin months. Tried cauliflower at 9 months but DS never really liked it.
Some other first foods i did was avocado and DS LOVED it, to this day he will eat that first off of his plate. it is such a great first food. Sooo healthy for them. Bananas, prunes, pears, mango, papaya, sweet potatoe, applesauce, carrots, squash and peaches, blackberries. That was it for the first foods between 6-9 months. i still have my paper schedule with all the foods on it and the months i gave it. LOL!! Sorry if too long.
Good luck and have fun!!!!