Well this instructional is right up your alley with its simple formula for guard retention. As far as developing a solid technical base, try to spend as much time as you can sparring with people who are willing to do positional sparring at 70-80 % intensity.
For example, if you're working guard retention as in the video, it shouldn't be too soft, but if they pass, they should return to guard and start the process again and again so that you can repeated revisit the same sequence of operations. At some point, you will develop a sense of familiarity with the basic processes such that you can begin to tinker with individual elements of the position, i.e., what if I put my arm here, or my shin there, this time. Through the repetition and focused learning you can develop skill pretty quickly, like a musician doing scales.
Once you find what works well for you, then begin to drill it and use it full kill-mode sparring.
"One's actions alone define whether one belongs to a good family or a bad family, valiant or arrogant, and disciplined or undisciplined." -Lord Rāma, Rāmāyaṇa