Don't Install If You Aren't Prepared
Absolutely do not install the macOS High Sierra beta if you aren't prepared.
At the bare minimum, you need to have a current backup of your Mac, and you want to make sure you don't overwrite it while using your Mac with macOS 10.13 for the duration of the betas.
Even if you have a good backup, you need to make sure you have the time set aside to install the macOS High Sierra profile, download a large file and install it. Make sure you download on a home WiFi network and set aside at least 40 minutes to install once the first beta downloads.
If you are traveling, in the middle of a huge work project or otherwise busy, you should hold off on installing the beta. This goes for the developer beta and the public macOS High Sierra beta.