If the baby is not eating well, the first thing to do is to try to identify the cause of the problem. Sometimes, the baby may be sick or have some other problem that prevents him from eating. Other times, the problem may be more trivial, such as not being hungry or not being prepared to eat alone.
Once the cause of the problem is identified, try to address it in the appropriate manner. If the baby has a health problem, then it is best to consult a pediatrician for advice and treatment. If the problem is that the baby is not hungry, then you may need to adjust your feeding schedule or try some new foods.
In general, if your baby is not eating well, it is best to talk to your pediatrician for advice on how to address the problem.