For meditation, there seem to be as many methods as there are people. Some ways of meditating include focusing on your breathing, picturing yourself in a white room or space or 'happy' place that inspires a sense of peace or bliss within you, pictures a darkness with a flame that you feed your thoughts and impulses into until your mind is clear, chanting a name, word, phrase, or sound over and over, listening to meditation music, ect. My preference, which seems to be one of the easiest for me, is the breathing. I'll explain how to do a breathing meditation, and also go over what you should be trying to do as you start meditating.
The main point of meditation is to still the endless stream of mental chatter. In all forms of magic, your intent and will power is often the tipping point for success or failure, and a mind that is calm, still, and focused solely in the present moment of the magic working is going to be the most successful one in most scenarios. Your mind constantly natters away, making little judgments, spelling out words and sentences in your head, jumping from observation to observation, and generally making a jumbled chaos. Each thought and observation being examined and picked over by your brain takes energy and focus from you. It is okay to think about a good many of the thoughts going through your mind, but so many at once is distracting, and you do not fully perceive the world around you when lost in thought like this. Meditation slowly eases these thoughts away, choosing to ignore them, still them, and focus the mind on a single thing. In this case it will be breathing.
Do not set the bar too high for yourself. Meditation has to do with the brain itself, and if you don't do it already, then its going to be difficult at first. It will be hard to quiet those thoughts, and as you keep focusing, oftentimes more keep slipping across your mind. But do not be discouraged, just keep at it. Don't feel like a failure, it's natural. The only way to do this successfully is with practice. Astral Projection is another very good example of that lesson. After long enough, this will become very easy to you, and it will become effortless for some. Meditating actually causes parts of your brain dealing with memory, focus, and concentration to thicken, much like muscles do when used. This leads to lasting benefits, including a steady and calm mind that can focus more easily throughout life.
First, sit comfortably, either cross-legged, or in a chair, even lying down and standing up, though most prefer sitting. Keep your back up and relax.
Next, make sure to breath properly. Many people breath with their shoulders, and not their guts. The diaphragm in your gut area is the breathing muscle. Try holding shoulders still, while sitting up breath in and be sure to push the stomach out as you do, then breathe out while pulling the stomach in. This gets more oxygen to your brain and blood and makes you feel pretty good on it's own. For the purpose of my usual mediation, if I do count, I exhale and inhale for 4 seconds each, and pause between for 1 second.
Now for this mediation there are a variety of things to focus on. You can focus on the physical feeling of the muscles moving, the lungs expanding, the feeling of air going into your nose, into your lungs, and out your mouth. You can focus on the smells, you can mentally say in and out on each breath, focusing on both the word and the action. As you are doing this, feel the stray thoughts in your mind gather up as you breath in, and then as you breath out, feel or picture them flowing out of your mind and away from you. Keep doing this for as long as necessary. You can even continue the act of blowing that cleaning wind through your mind, and it on it's own can be a form of meditation.
For timing, you can get some benefits from 5 minute sessions in a pinch, but the real benefits will be had when you do them from 10-30 minutes at a time, and doing it a few times a week would do you good, though meditating daily is good thing to make a habit of doing.
Again, there are many many ways to meditate, and some methods will come more naturally to some and not to others, and vice versa. Creativity and imagination are useful when thinking of ways to meditate and find something that works best for you. Feel free to experiment.
Peace and Love,