It's always best to start at the beginning. :)
Little babies are just that---BABIES!---and should be cuddled and cared for with infinite gentleness.
I am not advocating harsh discipline of these little ones, only gentle, consistent training.
I believe in a strong, intimate attachment between parent and child that is encouraged by breastfeeding (when possible), responding quickly to baby's needs, a healthy daily routine, and the give and take of gentle discipline.
Between 6 and 12 months, you can start to teach your baby to:
---Look at you when you need them to listen. Gently turn their head to your voice and say, "Look at Mommy!" Even if they don't understand exactly "what" you're saying, they can start to learn to make eye contact with you. Parents teach "patty-cake" and "peek-a-boo", "so big" and "the wheels on the bus".....in the same way, you can teach "Look at Mommy!" by making it fun, repetitive, and a simple part of daily life. :)
---Sit on your lap without arching their back to get down. Of course, sometimes a nonverbal little one will communicate by trying to slide out of your arms, and if you're not needing them to sit at that time, you could let them down, but you can also teach them "no-no, sweetie, sit on Mommy's lap". Don't expect long periods of time just yet, but they should be able to sit through a short children's book or a simple meal without screaming or squirming to get down. :) (If they DO scream, outlast them. Do not let them get down until they are quietly sitting on your lap. An unwavering hold and a firm voice quietly saying, "sit with Mommy" will help the little one yield.) Begin now to teach your little one to sit on your lap. You will be able to sit at nice restaurants, doctors appointments, and such, without your baby screaming to get down and explore.
---Understand the meaning of the word NO. We use "No touch" or "not for 'baby'". Young babies need to explore their environments, but there will always be a few things in their reach that are not for them to touch. Redirection is certainly appropiate at this age, but don't forget to teach while you're distracting them. For example, baby crawls over to the t.v.. You can say, "Baby, look at Mommy's eyes. No touch. That's not for baby. Here is a toy just for you!" with a smile and a redirection, all while still teaching simple obedience, beginning listening skills, and eye contact.
---Use basic signs to communicate their needs. Baby sign language relieves frustration in nonverbal babies! Teach them "please" and "more", "drink" and "eat", etc by using the sign while you say the word. Once your baby demonstrates that they are fully capable of using the sign for what they want (different age for each child), require them to use the sign. (Use wisdom here---if the baby is tired or really hungry, don't use that as a training time. :)) But if they start fussing for "more", don't give them more until they sign for it. Don't get angry or even frustrated. Just don't get them what they want until they obey. This will make training them to use "please", "thank you", and "yes ma'am" much easier later on. :)
Between 12 and 24 months, besides the above skills you can teach your little one to:
---"Come" and "Stop". We usually wait until our littles are walking steadily before teaching them to come when called or stop on command. Obviously, these are safety obedience skills, and while we teach and expect our children to obey, protect them from situations where their disobedience would result in harm. You can teach "come" and "stop" with a young child by making it a game. We even offer a reward (one jelly bean) for toddlers playing the "come" or "stop" game. Practice it daily. What about the toddler who has learned to come but then doesn't listen? At this young age, helping them obey is very effective. Call the child's name. Watch to see if they come. If not, go straight to them, get eye contact and say, "Mommy told you to 'come'. You need to 'come' right away when Mommy calls you!" Then take them by the hand and walk them to wherever you were when you called. Praise them, "Good job! You came to Mommy!" and then go about your day. This is not an area of discipline so much as teaching beginning listening skills. Many reminders will be necessary. :)
---Stay within boundaries you create. Blanket time, playpen time, highchair time, etc. These are not for discipline, but for training. Besides, if you make it fun by having a fantastic attitude, your little ones will think they are getting to do something really special. :) If your little one will not stay where you tell them to stay, back-track and teach them to sit on your lap without fussing or screaming. Outlast the temper with a firm, "No. You will not get up until you obey Mommy. Sit quietly." Wait patiently until they are willing to sit quietly. Don't bribe them with toys or distractions when they're being willfull, but when they do yield, give them a small toy or book to look at on your lap. Practice this daily, then you can move on to blanket time, etc.
(On a side note, we love to keep our babies near us. Teaching them a little self-control allows us to take them everywhere and enjoy having them close by. I also love to incorporate my babies and toddlers in my day...if I'm vacuuming, they're on the bed watching. If I'm taking a shower (and they're awake) they're on a blanket with toys on the bathroom floor. :) When I'm cooking, they're in a highchair with puzzles and toys, close enough to be a part of daily family life. At church, they're on my lap or in a sling. When I'm folding laundry, they're playing at my feet or sitting on top of the washing machine. Mommy/baby togetherness is important for attachment and a baby/toddler that obeys simple instructions is much easier to keep nearby at all times. :))
Once your baby has learned to look at you, to listen to your voice, and to respect that you are not going to give in to screaming, you have the basics of obedience.