use a kneeboard and write everything down.
before making the calls i write down my hdg, qnh and altitude, when the controller gives me information i write it down as they speak, so that i can read it back immediately. i also have the squawks and qnh/qfe written amongst any other instructions written down should i need to refer to them later.
i am a low hours ppl pilot and i guess i will learn to memory manage a lot more easily once i gain experience, but the above method works perfectly.
hope this helps