If you get the error message avrdude: Error: Could not find USBtiny device (0x1781/0xc9f)
That means the bootloader wasn't active. Make sure to press the button on the Trinket to activate the bootloader before clicking the Upload button.
If you get a lot of red text, errors and also a warning about Verification Failed
Check that you updated the avrdude.conf file above - if you don't update the description of the Attiny85 in the configure file by replacing it, the IDE wont know to be patient with the Trinket/Gemma bootloader and will have many upload errors
On Linux if you get the error message "usbtiny_receive: error sending control message: Protocol error (expected 4, got -71)"
These can generally be ignored and should not interfere with the program upload. Unfortunately Linux's USB core is a little flakey communicating with the ATtiny85 processor on the Trinket/Gemma and can cause these errors. If an upload does fail, try it again as it is likely an intermittent issue.
