Developing a game plan!!!

The basics of each phase of the game
Opening:
Follow the Opening principles:
1. Control the center squares – d4-e4-d5-e5
2. Develop your minor pieces toward the center – piece activity is the key
Ø Complete your development before moving a piece twice or starting an attack.
Ø Move pieces not pawns.
3. Castle
4. Connect your rooks
Ø By move 12, you should have connected your Rooks, or be about to do so.
Middle game:
When you have completed the Opening Principles, you are now at the middle game. Now you need to formulate a middle game plan. The middle game is a very complicated part of a chess game. A simple way to develop a middle game plan is to perform the following steps.
1. Scan your opponents 5th, and 6th ranks (3rd, and 4th if your black)
2. Look for weak pawns, and or weak squares.
Ø Weak pawns and squares are Pawns, and squares that cannot be defended by another Pawn.
Ø Knights are excellent pieces on weak squares.
Ø When deciding on weak squares, and weak Pawns to attack, the closer to the center the better
End game:
Start with the basics:
1. Learn basic mates – KQ vs. K, KR vs. K, KRR vs. K
2. Learn Opposition, and Key Squares
3. Learn basic King and Pawn endings

You're talking about the middlegame. Plans in the middlegame seem to stem from only two sources of which I'm aware: (1) the type of attack implied by the opening; (2) an attack based on an imbalance created from a mistake, meaning an unsound deviation from opening book was made that can be exploited.
Some helpful books for me were:
For (1)...
Fine, Reuben. 1989. The Ideas Behind the Chess Openings, Algebraic Edition. New York: Random House, Inc.
For (2)...
Silman, Jeremy. 1999. The Amateur's Mind: Turning Chess Misconceptions into Chess Mastery, 2nd Edition/Expanded. Los Angeles, CA: Siles Press.
Chernev, Irving. 1998. Logical Chess: Move by Move. London: Faber & Faber.
Chernev, Irving. 1965. The Most Instructive Games of Chess Ever Played: 62 Masterpieces of Chess Strategy. New York: Dover Publications, Inc.
However, overall, this is a difficult topic for the most difficult phase of the game, and in my opinion really good books on plans do not exist.

See if you can get a copy of GM Larry Evans' old book New Ideas in Chess. It was written back in the 1950s, so they are old ideas now... but still valid.
That book will show you how to perform a static analysis of a chess position. When they hear the word "analysis", most chess players think of the "I-go-here, he-goes-there" calculation process. That's the dynamic analysis. Rather than looking at potential moves, the static analysis breaks down the position into elements such as Space, Time, Force, Pawn structure etc, and then offers some general advice based on your scores in those elements.
For instance, if you were roughly even in Space, behind in Time but ahead in Force, the results matrix would advise you to play carefully, watch out for enemy combinations, avoid pushing Pawns, and try to exchange off your opponent's most threatening pieces.
I find that the concepts involved in GM Evans' book... not the actual counting process, but just an awareness of the concepts... is helpful in choosing a middle-game plan.
Other than that... study Pawn structure. It's the key to understanding strategy.