While trying to upload code from the Arduino IDE to my EL Sequencer I encountered the error message, "avrdude: stk500_getsync(): not in sync: resp=0x00".
1) Set board and port (there is ample documentation about this). 2) Enable verbose output during upload (hold down the shift key while clicking on the upload button in toolbar. There is also a checkbox setting in preferences) 3) From the verbose output I observed the IDE was Sending data but the board was not Receiving it. 4) I resoldered the Receive header pin on the El Sequencer used to connect the FTDI cable/breakout board. 5) Voila! Program uploaded successfully.
Hope this helps.