It would be best if you did not take your personal laptop. Get a cheap chromebook and put your important data on a cloud service of some sort. Once you pass through customs you need to completely wipe the laptop, re-install a trusted version, then pull down the data you need. Wipe the laptop again before you leave and be prepared to just leave it behind if it ever left your physical control during your trip. Find out which VPN services are currently working from China and also familiarize yourself with shadowsocks.
You need a disposable phone that does not have any data on it (contacts, notes, photos, etc) that you do not want to share with the Chinese government. If possible you should get a SIM card from Hong Kong and use that since it is less likely to have VPN and other connections blocked.
Beyond this you should look to some of the online guides out there targeted at journalists and how they can protect themselves, most of the same rules will apply to you in this situation.
Why is it best if I don't take my personal laptop? That would be pretty hard for me - I'm a student and live through my laptop, I probably can't afford even a cheap replacement.
I'd be open to backing it up before I leave, and then wiping it before I leave and after I return. Is that enough?
If my options at the border were to give someone full unsupervised access to my entire digital life or refuse and be inconvenienced for several hours it outright denied, I'd much rather give them something I can throw away after.
I know I'm not important, but my data is, to me. If I took your toothbrush to a back room for an hour without telling you what I'm going to do with it, would you still use it?
After reading the occasional story about Chinese [0] and US border BS every now and then, for years, I just don't want to take that risk.
You need a disposable phone that does not have any data on it (contacts, notes, photos, etc) that you do not want to share with the Chinese government. If possible you should get a SIM card from Hong Kong and use that since it is less likely to have VPN and other connections blocked.
Beyond this you should look to some of the online guides out there targeted at journalists and how they can protect themselves, most of the same rules will apply to you in this situation.