Can any one pls tell me how to increase MC's Skill levels without cheating
You likely found your answer by now but I'll write this for anyone else who wants an answer:
Intelligence is increased once a day at school by studying
Charisma is increased at night via the club
Strength is increased at night at the cafeteria by fighting
Stamina is increased once a day by running at the park
Luck will be implemented in a later build of the game.
Hope this helps.