Making milk kefir is really simple that anyone can do it. And yet, learning how to distinguish the grains from the curds and troubleshoot when things gone wrong, can take just a little time, patience and practice. To order milk kefir grains or ready to eat milk kefir, see bottom of this page.
When you receive your live milk grains, transfer everything from the bag and put them into 1/2 C of milk immediately. Use a glass jar and leave the lid loose to allow some airflow. You can use any type of milk, but the grains prefer the most natural source- raw milk. And if raw milk is not availabe, then use whole milk. It should do fine in any type, but less processed the better. Also, higher fat content tends to produce thicker and creamier kefir. Make a note of the date and time you start this process so you will know how long it takes to ferment in your kitchen.
Let it sit at room temperature, away from direct sunlight. After 24 hr, you may see whey pockets forming. Even if you don't see whey pockets, drain the milk out and put the grains back into the same jar (do not wash or rinse the jar out) with another 1/2 C of fresh milk. If you give the jar a swirl every now and then, the aeration will speed up the fermentation a little bit.
It's normal that the first few batches of strained milk may not smell or taste good, but it is not spoiled. You can save the strained milk for baking or cooking such as muffins or pancakes.
After several batches, the grains should start to adapt to their new environment and food source, and should start making whey pockets (clear liquid pockets that forms on the bottom of the jar). As soon as you see the first whey pocket, kefir is ready. The consistency of the kefir is like a very soft sour cream or yogurt at this point.
Use a spoon and stir the mixture very well. You want to break up the curds from the grains. Drain the kefir through a fine mesh strainer to get the grains out. This may be a very tedious process if you over ferment and the curds are very large. Just be patient and strain a little at a time. Use the spoon to break up the curds and tap the strainer on the container to quicken the process.
Put the grains back into the same jar and add fresh milk. Clean the outside and rim of the jar and it's ready to make the next batch. In case you are wondering about washing the jar, you don't need to. As long as you started with clean utensils and clean hands, these beneficial bacteria and yeasts will keep the airborne bacteria & fugus away. That is one of their functions. They are anti-bacterial and anti-fungal. Pretty amazing stuff!
When the grains are fermenting the 1/2 C of milk properly, double the amount of milk next time. You can keep doubling the milk up to 3-4 cups. I use 1/8 tsp per 1 C of milk so you should be able to make one quart with 1 tsp of grains, once they are adapted to your kitchen. In the meantime, you should also noticed the grains are multiplying slowly.
Once you've drained the grains out and started another batch, you can drink the kefir as is at room temperature. If it's too sour to your taste, you may add some honey, jam or other sweetener to your liking. Many people like it cold. Store the unused kefir in a bottle, room temp or in the fridge.
Since kefir contains live probiotics, you need to know that it will build up pressure inside the bottle over time, even in the fridge. That is perfectly normal. After 1-2 days in the fridge, the kefir will be slightly effervescent. This is even better because it contains more B vitamins when this occurs.
If you need to take a break from making kefir, just put the grains in the same amount of milk, and store it in the fridge. It should be fine for 1-2 weeks or so. The grains will continue to ferment the milk in the fridge, but at a much slower pace. When you are ready to make kefir again, take the jar out of the fridge and leave it at room temperature. The kefir will be ready soon. This way, you are not wasting any milk.
There are much, much more valuable information here on Dom's kefir-making site.