Dizziness may occur during the first one or two days. Take a quick break, it will pass.
Headaches may appear at any time during the first weeks. Try to relax. Take any usual remedy for headache, a cold cloth on the back of your neck, or relieve the stress by taking a short walk.
Tiredness may occur during the first few weeks, but if you meditate or relax during the first few weeks, it will pass.
Coughing may actually increase during the first few days, simply because the residue from the smoke has not been flushed from your system.
Tightness in the chest may occur in the first few days. Rest and take deep breaths, it will go away.
Sleeping problems may occur in the first few days. Try to stay away from drinks that have a high caffeine content and try not to exercise too strenuously in the hours prior to bedtime. A hot bath prior to retiring at night may also be helpful.
Constipation may occur in the first month after you quit. If this occurs, eat foods with a high fiber content, drink plenty of fluids, and do some light exercise.
Concentration may tend to wander during the first few weeks. Be ready for this, take a break or do something physical for a short period of time.
But...it will all be worth it!