Thing not to do in Ramadan:
Missing Prayers: Salah (prayers) are the second pillar of Islam. It comes before Saum (fasting).
Eye Side : Looking/oogling at a women is not best be avoided.
Listen: Don’t listen those things which are haram (prohibited) such as gheeba, gossip and music.
Tell: Don't speak without purpose. Back biting is considered more sinful. Avoid telling lies or gossiping. Don't argue.
So if you think that talking on the phone or meeting friends might result in back biting then avoid it.
Abusive language : When you abuse someone it doesn't harm him, it just adds to your sins.
The Hand : Don't get into fights, stay away and if you get into one and loose your temper, practice patience (sabr) and walk away.
Don't Waste Time : Try and cash every moment by doing Dhikr.
Attitude: Don't be vulgar, rude or swear. Don't be irritable. Don't be boastful or arrogant.
Avoid:
Fried and fatty foods.
Foods containing too much sugar.
Over-eating especially at sehri.
Taking too much tea, coffee, soft drink, especially at sehri.