Getting married is the most important moment in a girl's life. As her good friend, you must send her your sincere blessings. I recommend you to give her a gift of money + red envelope. It doesn't matter whether the gift is expensive or not, as long as it represents a thought. You can choose it according to your financial ability.
As a wedding gift, you must choose a festive gift, which can be a handicraft that represents good luck, or a creative and romantic customized gift. You can use your friend's wedding photos to create a pair of ceramic statues, which must be a unique gift; you can also use photos to customize a crystal piano music box, or give a pair of Tang suit wedding dolls. These gifts are generally priced within 200 yuan and are very popular among fashionable young people.
Secondly, small appliances and bedding are more commonly given as wedding gifts. If the relationship is very good, just ask her directly how the preparations before the wedding are going, what is missing at home, or what gifts she likes.