Take a screw driver +/-(depends on your remote) and carefully remove the screws and keep it safe.
Step2
Remove the back cover with care and separate the key panel and the remote board(the circuit board)
Step3
now place the circuit board above a paper and clear it with a soft dry cloth.
Step4
take few drops of kerosene or any mild detergent on a damp cloth and gently wipe on the circuit board, you can see a blackish settlement on the cloth after you wipe it. its the dirt. Blow it manually or use a blower.
Step5
leave it aside for a minute. Then with a another dry soft cloth make a final wipe and ur remote is clean.
Step6
Now you have to properly place back the key panel and the circuit, after that close the back cover with care and re screw it.. Done
Tips & Warnings
Whatever you do, be gentle, wipe it slowly and lightly.
Do not use any other substitutes for cleaning.
Take care when you wipe the circuit board, excess wiping might lead to damage of the circuit.