It depends on your current ability. If you have a job, you should give your sister a red envelope. If you are still studying or working like that, it depends on how old you are.

1: You have already joined the work. The best red envelope is 1680 yuan (all the way).

2. You are under 20 years old, but you are older than 17 years old. If you don't have a job, you can take 600 yuan (666 Shun) or 800 yuan (88 Round).

3: If you are younger than 17 and are still studying, don't wrap a red envelope. Go to your brother-in-law, and your sister's brother-in-law will give you a red envelope. Generally, the red envelope I give my brother-in-law is 1000 yuan.