i feel it difficult to think accurately.... specially when it is too long moves...

Most players suffer the same ill. It IS difficult to think accurately, to identify and consider only reasonable candidate moves, to avoid returning to analysis of lines you already reviewed, to keep from making a stupid move that you didn't even seriously evaluate. These are all ills that all players suffer to one extent or another. Many whole books have been written on this subject, some becoming classics (Kotov's Think Like a Grandmaster) without being approachable, helpful, or even correct.

Join the club.

An interesting book (though not at a complete amateur's level) is Jonathan Rowson's Chess for Zebras.

He attempts to answer questions like "Why is it so difficult to improve and What kinds of mental attitudes are needed to find good moves in different phases of the game?"

You might give it a try.

Good luck.

so u r an impatient kid .......

lol u need patience

Deep Meditataion is required for such problems.