My elder one is always bullying his sister, how can I improve the situation?

Is there a reason you could think of why your son is bullying your daughter? Kids are simple little creatures and are generally easy to solve if you can get to the root of the problem i.e. jealousy, envy, lack of attention, etc. I have a 7 year old daughter and a 7 months old son, and I often get my daughter involve with her brother as often as possible. Also, I enforced a habit to kiss her brother goodbye/hello whenever she leaves home for school or comes back from school. Also, if I buy say for example a set of outfit for my son, I have to remember to get an outfit for my daughter too so she wouldn't feel forgotten or replaced. Sometimes I bring her out for mummy-daughter dates to catch up with her and these are the times I noticed that she would open up to me a little more and find out if there is anything bothering her.