Introducing Meats??

So, currently starting introducing solid food to my baby girl.... so far she's had rice cereal, oat cereal, sweet potatoe, carrots, and avocado. My doctor has suggested that I start her on meats. This got me thinking....I have to mash up meat...and add....water? How do you know what meat is safe to feed your baby? What kind of beef do you start with? I realized there's more to feeding solid foods to your baby than just mashing up food. So I ask you all this.... How do you introduce meat to a 6 month old baby?? Please help!