Book Recommendation: Love and Logic Magic for Early Childhood by Jim Fay and Charles Fay, PhD. (http://www.loveandlogic.com)
Setting limits and enforcing then is a basic foundation for healthy parenting. Your little one doesn't have to have a handle on the spoken word to be able to learn. Their little brains are amazing. In the first few weeks of life they build trust with the person(s) who care for them as they learn "cause and effect." They learn, "If I cry when I am wet ot hungry, this loving person will feed me and change me." It doesn't take long for them to discover they can use their crying to communicate other information as well. ( I'm bored. I'm angry.)
Parents can use the basics of Love and Logic very early by reinforcing their childs understanding of cause and effect. For almost any behavior, lead with empathy followed by a small "effect" or consequence. For infants that's usually restricting movement by holding arms or legs down very gently and briefly or removing an object, changing your location, or changing the child's location. A grandmother I know uses a sing songy "Oh no that's not good!" She sings the phrase in a very empathetic way then explains why baby has to lose the object they were misusing or be removed from what they were doing. She uses the strategy of moving them to a blanket in the corner for just a little bit. This grandma says that now all she has to do is start singing "Oh No" and the unwanted behavior stops. Using the same phrase everytime has helped the little one's in her care understand "cause and effect."
Baby squirms during diapering: " Oh No! I'll have to hold you still until you stop moving. "(Gentle holding)
Baby throws food: "Oh No! That's not good. Eating is over, down you go." (Change baby's location from high chair to floor.)
Baby is hitting a coffee table with a toy: "Oh No! That's not good. I need to take that toy now." ( Remove the object frm sight.)
Any smart baby will try to control the adult with crying at this point but empathetic reassurance that you love them (without giving back the offending object etc.) will help establish in their minds that crying will not cause adults to relent. This can be very hard on the soft hearted parent. Be assured you are blessingb them in a powerful way by holding firm in instances where it is clear they are being willful. However, at all other times, respond immediately, establish a warm loving relationship, and enjoy the age.