First of all, of course, you should bless her, then you can ask her what help she needs. Do your best to help her. There are many things to be busy with when getting married. If you have many friends, you can help your sister consult, buy things, find a wedding, find a car and order drinks. Too many.

As a gift, you can ask her what she likes, give her money directly, or give her a small household appliance, depending on your financial situation.