You're tired. You aren't sleeping. Your baby isn't sleeping. You've scoured the Internet searching for answers as to why your child is still waking up several times a night and won't nap longer than 30 minutes at a time and you have come to the conclusion that: you need to sleep train. Perhaps baby is nursing to sleep and this is causing every hour wake-ups, or maybe your little one is addicted to the pacifier and Mom and Dad are doing the paci dance all night long. Either way, everyone needs more sleep and it's time to devise a plan to make that happen.
Sleep coaching a child is never easy. But sleep deprivation is even harder. If you have come to terms with the fact that a little coaching is in your future, here are some steps to take before you begin any plan to get your family back on track.

Make sure you are well-informed about baby sleep. Read up on how much sleep your child needs, how many naps per day your child should be taking, how long your baby should be awake during the day, and why early bedtimes are important. Also, read up about dependency issues and make sure you are aware of why your current sleep situation is not working, as this will help you to be consistent during the hard times.
Pick a sleep coaching method. There are many different methods available to use and they range from gradual (especially for younger babies) to more direct (for older babies or parents that are looking for quicker results). Make sure you and your spouse are 100% on the same page about the method you choose because the most important part of any sleep coaching method is being consistent. All methods will work as long as you are willing to put in the time and effort for as long as it takes.
Get rid of all the sleep props. This means the paci, nursing to sleep, co-sleeping (all or part of the night), rocking/bouncing/shushing, the swaddle, etc. We want baby to be able to go into his crib wide awake and put himself to sleep.
Make sure your child's schedule is age-appropriate. No sleep coaching method will ever work on a child who is overtired. Make sure you are not keeping your child awake too long during the day, and especially not before bedtime. Early bedtimes are especially important during sleep coaching as naps may be shorter for the first several days/weeks. Keeping your child up longer in hopes that he will 'crash' and sleep better will only backfire. Babies fall asleep easiest and stay asleep longest if you get them to sleep at the peak of sleepiness. Well-rested children accept sleep more readily, sleep better, and sleep longer than overtired ones.
Pick a start date. You want to pick a day when you know that your spouse/relative/friend will be able to help provide support. You also want to be sure you can dedicate at least two weeks, and preferably a month, without any major disruptions (i.e. travel). Some families may choose to work on nights first, and once those are in order, move onto naps. This is a great plan if naps are already decent as it helps to avoid overtiredness. Regardless of whether you decide to tackle naps and nights at the same time or not, you always want to make sure you begin any sleep coaching plan at night, when the drive to sleep is higher.
Prepare the environment where your child will be sleeping. Make sure your child's room is dark for naptime and for nighttime. If you think of it on a scale from 1-10, 1 being bright and sunny and 10 being pitch black, we want that room to be an 8-10 during the day and at night. No nightlights, projectors, etc. as these are too stimulating. Use room-darkening shades or you could even go a step further and use tin foil or black construction paper on your windows. You won't win any design awards but your child's sleep will certainly benefit! Make sure baby's crib is safe and boring. No toys, mobiles, etc (a small lovey is alright if you are comfortable with it). As well, white noise is a must. Make sure the white noise is loud and continuous (no 45 minute timers). You can even use a fan or a radio set to static if you do not want to purchase an actual machine (although I think this is a very worthwhile investment!)
Establish a plan for the middle of the night. The middle of the night is usually parents' downfall. It is much more difficult to remain consistent in the middle of the night - you just want to get back to sleep and the only way you can do that is if your child is asleep too! Although it's difficult, it is important that we send the same message 24 hours a day. Keep your expectations for the middle of the night realistic. Remember - just because a child knows how to sleep does not automatically mean that he will sleep through the night. Help him do so by minimizing overtiredness and having an appropriate sleep schedule. Read here about average nighttime sleeping habits for babies and decide (with the help of your family doctor) how many feedings you feel comfortable with at night and stick to it.
Write down your plan. Putting it on paper will help you to be consistent. Include your sleep coaching method, the rules you will follow, the habits you are trying to quit, and how you will handle middle of the night wakings. Refer to this plan often, especially in moments of weakness!
Keep a Sleep Log. This is so important in order to track progress and see patterns. There are many different websites devoted to tracking sleep, but plain 'ol pen & paper also works great!
Start! Give your chosen method a full week before deciding if there are things you need to tweak. It also takes that long for baby to realize the old way is gone and the new way is here to stay. It is also very normal for a 'regression’ or ‘extinction burst’ to occur between nights 3-8, so be prepared for things to potentially get a bit worse before they get better! I mentioned it before but I'll say it again, the most important aspect of any sleep coaching method is consistency. Remember - teaching a child healthy sleep habits is a way of life. It does not end after just 1 week of "training".