It's not enough these days to simply say "Hi, welcome to our store." You should have a reason why your business is the perfect spot for them to have entered.
That doesn't mean every day has to be some kind of Open House celebration-event. It just means that you should be prepared to tell customers what they are going to find today when they are in your business.
It could be that you have a new arrival of product, and they can be one of the first to see it. It can be that you have just started a contest, and aren't they lucky they get to be one of the first to register. It can be that today you have new sale product on the close-out table, and they get first choice.
You get the idea. You have to create a reason for the customer to walk in. You as the owner have to create a reason that your staff is excited enough to convey. If you don't have a reason, don't expect your customers to find one on their own. You create the excitement, you create the event, and you cause the customer to feel that they are in the right place.
Your enthusiasm will be contagious infecting your customers and staff. It will make you feel more connected to your customer and the customer will be thankful for your help. It will help you to build a deeper relationship with those that frequent your store and will brand you as a "go-giver"(someone who truly cares about their customer).
People tend to want to help and support people who help others. If people know that you're not a "taker" (someone who expects you to frequent their business), they're going to be more inclined to share their positive experience with your business to their friends and colleagues.
Or, you can say: "Hi, how are you?" just like everybody else and give the customer no reason to be excited that they've come in your door.
The choice is yours.