Make sure to check your passport prior to scheduling any trip outside of the contiguous 48 states. I cannot even begin to tell you of personal horror stories from my friends who book international travel only to find out their passport will expire while they are traveling! It is very time consuming to renew passports except in the utmost emergency.
Make sure to arrange any visa interview appointments prior to leaving the US. Right now, US Consulates are still not entirely open worldwide and it is not so easy to just schedule an appointment to renew a visa. Plan ahead!
If your lawful permanent resident card has expired, but you have a valid receipt notice extending the card, you can safely travel abroad. Remember, you must have a passport valid for 6 months past your re-entry date. With the passport, your lawful permanent resident card and receipt notice, you can re-enter.
When traveling abroad, keep your passport with you, but also bring a copy to keep in your luggage in case it is stolen or lost during your trip. Better yet, keep a copy in the cloud. If you ever need an emergency re-entry document, you will be able to access this from anywhere.