Personally I fit my own cleats (with no previous experience) and it was not that hard. I followed Steve Hogg’s series on foot correction and cleat positioning, the first of the series can be found here: http://www.stevehoggbikefitting.com/...-arch-support/
For reference I use the Shimano XC30 shoe, which is an SPD cleat, so that I can use the shoes on a spin bike when exercising at the YMCA.
For cleat positioning I did the following:
For the fore-aft adjustment
I followed the Steve Hogg method and have had great success and no knee pain. I followed Method 2 at the following link: http://www.stevehoggbikefitting.com/...leat-position/
. I would recommend Method 1 or 2, but probably not 3. To find the 1st MTP and 5th MTP use this method: http://www.stevehoggbikefitting.com/...w-their-nails/
Next I set the cleat angle (toe-in/toe-out angle)
to ensure that my heels did not hit the crank arm and that my feet were in-line with my knees. To do this:
1) sit on the edge of a table with the edge of the table touching the back of your knees so that only your knees down are hanging off the edge
2) Relax your legs and feet, put my knees pointing forward, and observe the angle of your feet relative to an imaginary straight line from your hips out through your knees
3) hold the shoe in one hand and the cleat in the other and twist the cleat angle until the shoe matches the angle of your foot, but the cleat remains pointing straight
4) loosely tighten the cleat bolts.
To test if I had the right angle for each foot, I rode the bike for 30-45 minutes and determined if I had knee pain. I did have pain in my right knee, because my toe-out angle is very extreme so I set the cleat angle as far as I could and that fixed the pain issue.
Since my toe-out angle was wide, I set the Q factor (controlled by the lateral position of the cleat on the shoe)
so that the cleat was all the way towards the inside of the shoe. This resulted in my feet being towards the outside of the pedal and my heels clearing the crank arms. If you do not have toe-in or toe-out, you should set the cleat so that your heel is roughly 2cm from the crank arm while pedaling. Have someone stand in front of you and watch you as you pedal backwards to see if you knees are in-line with your feet.
Lastly tighten your cleat bolts and fill the hex holes with candle wax to prevent debris from making it hard to change your cleats later.