I am a Reiki II practitioner and have been attuned to Usui Reiki since February of this year 
Let it be clear that i am not asking your opinion on the existence of Reiki, I am asking if anyone has any exercises that help strengthen the energy flow you channel? 
Thank you sooo much
Love Light and Peace:)
Practicing as much as possible is the best way to strengthen your channel. Practice on as many different people, animals, and plants as you are able – don’t forget daily self-treatments. The clearer your own energy channels are, the better the Reiki energy will be able to flow through you. And the more you practice, the more your ability to sense and indentify differences in the energy, which will in turn build your confidence further. Also, since it’s like any other exercise routine, the more you practice, the more adept you get.
To the end of clearing and strengthening you own energy channels, you may also wish to begin a daily program of working with your chakras. I require all my Reiki IIs to begin a chakra practice of some sort, and provide them with some guided meditations to get them started. The stronger and clearer you get your energy flow, and the more Lightenergy that you body can comfortably hold, the more Reiki energy will be able to flow through you. There are all sorts of different methods out there. Again, self-treating is one way, though I would like to see you taking a more conscious/active approach through meditation. If you Google "chakra meditations" you’ll find ALOT out there – surf around and see which one’s you like best. I recommend a program that includes chanting/toning as well as visualization of the colors and energy. Bringing the vibrations of sound in the meditations makes it extremely powerful. My ALL TIME FAVORITE chakra meditation cd (actually you can get it as an instant mp3 download for about $10) is called Chakras Gone Wild by Allen Burns: http://www.metastudies.com/store/product.php?xProd=211
If you get it (or any other album that includes chanting or toning on the appropriate notes and syllables) make sure to chant/tone along with it as you meditate on the various colors of the chakras. Chakras Gone Wild lasts about 5 minutes on each chakra, so you can do the whole thing in about 35 minutes, and it’s alot of fun and VERY effective. It layers chanting of the sanskrit mantra of each chakra, done in the corresponding musical note, with soundscapes also designed to awaken the chakra. It’s really amazing. I use it all the time, and it’s part of my chakra balancing treatment package that I have for clients.
Another really amazing way to help "strengthen" your channel is through mindfulness meditation. The largest impediment to your channel is your ego, so the more you can let go and get yourself out of the way of the energy, the stronger the energy will come through. This is one of the true core lessons of Reiki, but sadly most Western classes do not give instruction on the basic methods that one can use to develop their ability to let to. Mindfulness is really one of the best, and the easiest to learn (although difficult to master, as any form of meditation is).
A great site where you can learn more about it is http://www.wildmind.org/mindfulness. I can’t recommend it, and the practice of mindfulness enough. It teaches you to let go and just "be" with as few attachments as possible to your thoughts or your surroundings. You become very present and focused on the current moment without clinging – and THAT will allow the Reiki to come through the most clearly and strongly. I teach basic mindfulness meditation as a part of all my Reiki classes.
There are also exercises that come out of the Japanese Reiki traditions that are meant to help strengthen your connection to the energy.
Here are some links to some of those exercises:
http://www.threshold.ca/reiki/ – this is a pretty comprehensive page, just click on the various exercise titles in blue, and you will be brought to a seperate page describing the exercise and what it is meant to accomplish; Hatsurei-ho is the exercise specifically for increasing your channel.
http://www.reiki.org/reikinews/reikimeditation.html: this is a 21 day meditation routine designed to help clear and open you to greater amounts of energy.
Also, if you have any friends who are Reiki Masters, ask if they will give you repeat attunements. The one-time-attunement method that we know know was not part of Usui’s original Reiki system. He provided regular "empowerments" called reiju. Getting new attunements can act as a kind of reiju by providing you with an extra large burst of energy for your body to utilize for clearing and charging. It’s not necessary, obviously, but I do know that some practitioners that like to get new attunements on a regular basis for this reason. If 2 Masters are friends, they may swap from time to time. Again, this is not necessary, but can help increase your own energetic health and stamina, which will increase your channel.
Hope these ideas have helped – but honestly, the best way is just to PRACTICE!! You’ll eventually develop the abilities on your own, but these are some ways you can help speed things along!
Blessings!
