Giving free gifts according to customers' interests or needs is important. It's a bit hard to know your customers' interests. But you can also give free gifts according to the weather.
I remembered a scene in an old movie that told me how to do business. The scene in the movie was about doing business in different season or weather. In the movie: a man gave his friend an idea of selling umbrellas during wet season and fans during dry season. This is a very common practice in business. But, to me (as a primary school student that time), it was a very logical and useful theory of business I had to remember (I was quite funny, though) . So, until now, I still remember the scene of the movie.
In doing business, never neglect promotion with free gifts. If you really want to think for the promotion, you will find a lot of great ideas for it, then use it on certain days or seasons.
Let me give you an example. If you own a provision shop selling rice, grain, etc, you can use my idea for promotion during new year (use it for Chinese New Year or maybe Idul Fitri). This is how:
On Idul Fitri, you can give out rice cracker (there are many kinds of rice cracker). If you just own a small rice business, you can give out homemade rice cracker for every customer. Don't forget to give a warm greeting. If you are afraid of losing money, you can set a target of gift giving according to their purchase.
Use keywords like: promotional gift wholesale or promotional merchandise to search of items you can use for promotion.