Stay healthy:
If you are not accustomed to food sold by street vendors, you might want to stay away from food sold on the streets until you acclimate. If you want to try a pupusa, you should try to find a restaurant to taste this popular dish rather than buying them from street vendors. That said, street food that you see cooked can sometimes be safer than restaurant food that you do not see cooked.
'Agua en bolsa' (water in a plastic bag) is very commonly sold in the streets and corner stores of El Salvador.
Pharmacies are easily found all over the country. Be sure to have a first-aid kit if you travel to the countryside and to archaeological sites. Mosquito repellent comes in handy.
Respect:
Salvadorans are known for their great hospitality. They are among the nicest people in the world. They are friendly, industrious people always willing to help anyone. That is what has earned El Salvador the nickname of "the country with a smile". When speaking with people you don't know, it is customary to address them in a formal manner, using señor, señora and/or usted.
Contact:
The international country code for El Salvador is 503.