All babies deal with pain in a different way, some will have an easier time of it than others. Most babies with get a little grouchy and irritable. The first signs of teething usually begin a few months before the first tooth appears so you will need to look for particular symptoms to ensure that this is actually the cause:

Restlessness,irritability and disturbed sleep patterns
Sore and red gums
Flushed cheeks
Loss of appetite
A slight rise in temperature
Dribbling
A desire to chew anything to ease the pain. This is a completely natural reaction to the changes that are going on within the gum and it is thought that chewing on something hard feels quite soothing.
Sometimes you can actually see the tooth cutting through the gum, or you may be able to feel it emerging if you run a clean finger along your baby’s gum line.