I was in the exact same boat. Or pediatrician told us to start with cereals at 4 months, which we did. It took my daughter about a week or two though to even take a bite! Turned out she preferred barley and oatmeal cereal to rice cereal, plus once we started veggies and fruits, she ate better. Just heads up -- don't get discouraged! Also, I did breastfeed my daughter exclusively, and when we started cereal, I used breast milk all the time. However, a few months later though I was still breastfeeding, I wasn't able to keep up with pumping, so I started making her cereal with formula. Took her some getting used to, but I added half a jar of baby food fruits to make it taste better. She ate cereal with the formula and fruit until she was about 11 months old when she decided she was done with baby foods. Good luck with the feeding adventure, and beware of the messes! :)
And, like the other response below, I too made my daughter's cereal very runny at first and gradually worked up the consistency.