New wheelset, spokes losing tension I recently got a new wheelset Reynolds Solitude from a friend. He bought a new bike and it came with these wheels so he sold them as take-offs. They have internal spokes. 
I have one problem with them not sure if it is related to the wheel set being new.

Spokes on my rear wheel, non drive side (laced radially) keep losing tension after ride. First time I had 7 spokes loose after 45 miles ride, I didn't feel any problem with the wheel as I was able to ride home. Took it to LBS they have trued the wheel and after that I got them loose again. 

I can not afford to go to LBS any time I have problem with my wheels so I am taking different approach. I would like to learn how to do it on my own so I bought ParkTool TM-1 for that purpose and a truing stand. 

Now I have a question : What is the process for fixing this particular problem, retensioning the radial side and truing the wheel? If anybody can point out things that I should do/don't do in order not to destroy the wheel?
If you are looking to learn about wheel building, google search Sheldon Brown. He has a website that is phenomenal. I highly recommend it. I learned everything I know about wheel building from a couple hours of youtube videos, the park tool bike mechanics book, and his website.

As for your specific question, I think overall the spoke tension throughout the wheel sounds like it is not enough and after tightening and truing whichever side it is that you are having trouble with I would do a quarter turn on each spoke in the wheel and ride. If it loosens up do another quarter turn on each spoke. With a properly laced and trued wheel with spokes at the proper tension you should never have issues with the spokes loosening.