Auto comment: topic has been updated by GGapa (previous revision, new revision, compare).

Practice more

Just solve some problems requiring tough implementation.

try to make the implementation details clear in mind before writing code

Well, I've had the same problem for a while. The key is to be on paper, write the details on it, complete it and think about how do u implement this, like imagine almost everything that isn't ordinary. and just writing the facts u got on paper, with details will be helpful, since ur mind doesn't need to handle all the facts now, and writing it will give u a better understanding of it, since u try to shape it into words and sentences instead of it being a light bulb in ur mind.

You can write a C++ game yourself. After written some games my implementation skills improved a lot. (Well I think it's because when you are writing projects, your mind is very clear about what you are doing and what should do, and this is very important in CP)

Also you can participate in ABCs.