The Pan-American highway travels through El Salvador and is a safe route for entering the country and travelling between San Miguel in the East and San Salvador in the West
From San Miguel bus terminal there are regular one hour bus rides to El Cuco. You can also get a $30 taxi or some hotels offer a shuttle service from San Miguel to Playa El Esteron via El Cuco
There are shuttles from El Tunco, San Salvador and Léon in Nicaragua ($45). There is also an extremely expensive boat from Potosí in Nicaragua to La Union ($75) from where you can take a short chicken bus or taxi to El Cuco.
From El Tunco/La Libertad you can take chicken buses, either down the coast via Usulutan or back via San Salvador and San Miguel.
Intipuca Beach is home to the first microbrewery in El Salvador and offers an array of hand-craft beers by the beach. You can also find several bars and liquor stores in El Cuco or for party-nightlife you can head to Ave. Roosevelt in San Miguel which has numerous bars and clubs open until the early hours of the morning and is also hosts to the biggest carnival in Central America in November.
There are regular buses that leave El Cuco for San Miguel bus station where you can catch a connecting bus to many other destinations inside or outside the country.
Some hotels offer a very expensive shuttle service to San Miguel or other destinations inside/outside the country - León, Nicaragua is a ridiculous $50.
La Tortuga Verde offers transport between El Salvador and Nicaragua (skipping Honduras) by private boat $200 for up to 20 people (as of November 2014 the cost is a rip-off $75 per person and don't count on arriving in Potosí Nicaragua in time to catch the last chicken bus).
To get to Nicaragua you can also take public transport (much, much cheaper than shuttles or the boat) - take a chicken bus towards San Miguel and get out at the main roundabout before the city. Change to bus 330 to the border at Amatillo, walk across, then take a direct minivan across Honduras to Guasaule (or a chicken bus to Choluteca and another bus to Guasaule). Walk a few hundred metres past the border, then take a bus to León, or a bus to Chinandega where you can change.