Paying for some membership or not, there is not really any one "trick" to help you know what to look for and when exactly. Luckily, pattern-recognition and practice hints at common themes to look for: the only drawback is that this takes a lot of practice and patience.
Obviously, practicing tactics and doing things like the chess.com lessons will undoubtedly help (one free once per day on chess.com with default (free) accounts. However, I think you are more referring to common positional ideas/themes. I would like to say that there is a simple answer, but there really is not - although I will say that many openings do often involve several common motifs to them.
Chess.com member "kindaspongey" posts huge lists in the forums that might be of interest to you. Basically, just try to have a plan of some kind at all times - even if it is as simple as "I will develop this piece." Chess is really about playing out your own ideas and trying to prevent your opponents' ideas. Hope this helps answer this somewhat 
Is there a short and concise guide on this? I mean, probably its behind the payment wall of this site. But I do not feel like doing another diamond membership, as life is too busy to benefit from it.
In addition, I am working through some ipad app that was recommended a couple of times. CT ART 4.0. Probably it is better than I realise for now. But it just tells you to look for a mate or a piece advantage. Now that just undermines the actual learning process for me.
Or maybe I am just looking at the wrong type of training.
Please help me out a bit :-)