Wherever you are coming from within El Salvador, you will likely have to pass through either San Salvador or San Miguel on your way to Suchitoto.
* From [wiki=0127e714ebf6a3a25e4fdd721ecb36ed]San Salvador[/wiki], take a direct bus (#129) from Terminal Oriental. The last bus leaves around 6pm, takes about 1 hr 30 min, and costs $0.70.
*From [wiki=bd10f8ed22bc839e3231f2cd424c336c]San Miguel[/wiki], take a bus in the direction of San Salvador and ask for the Suchitoto stop in San Martin (a small city on CA-1 close to San Salvador). Make sure they know you are headed to Suchitoto and they will drop you at or near the (tiny and unassuming) bus stop. The bus from San Martin to Suchitoto runs roughly every hour until 9pm, costs $1.30, and takes about an hour.
A ferry operates between Suchitoto and San Francisco Lempa across the lake. There is no specific schedule and the ferry operator will set off when he feels he has enough passengers.