Trying to calculate
One thing we can say for sure is that to calculate, you need some idea of candidate moves. One idea of finding candidate moves created by Cecil Purdy is this.
1. MY TURN TO MOVE.
What are the moves I have to consider?
At this point answering this question be unanswerable; however, if only given say two legal moves, then you can skip most of the system.
2. How has his last move changed the position? Has he made a threat?
Try and remember that just because you have a plan doesn't mean that your opponent can't stop you or create a strong and more well devised plan. keep up to date on the position.
3. complete the folowing if not already.
material. notice things like bishops vs knights, pawn majorities, bishops of opposite color, piece placement, etc.
King position. Is either king insecure or exposed to say checks?
Weaknesses and strengths. weak pawns, squares, lack of space. a good knight vsbad bishop, control over an open file?
development. Purdy considers the value of a tempo to be a quarter to a third of a centre pawn. And up to half of a flank pawn.
where could either side breakthrough. pawn levers and less likely sacrifices(greek gift for instance.)
4. do I have a good combination or a reason to look for one?
5. If the answer to question is yes, what is my best plan for this?
How can i exploit his weaknesses, make my strengths winning advantages, and eliminate my weaknesses.
2. WHEN CONSIDERING A CERTAIN MOVE.
1. Visualize the move as if it were made
2. Does it leave me vulnerable to any combinations?
3.WHEN IT IS MY OPPONENTS TURN TO MOVE.
Make a reconnaissance, do the previous steps, perhaps even for your opponent. get inside his head, think not just about your best moves but your opponents aswell.
This is an abridged version of jeremy silman's book "The Reassess Your Chess Workbook" which skimmed over the subject(the main point of the book being imbalances.)
though it is mainly proverbs and you can skim the steps if needed(for time reasons.) havin the steps at least in the back of your mind should help.
I'll now give some excersizes, hopefully you solve the position using these steps. If you have another way of finding candidate moves please speak of it in the comments.