My first failure :( What should i learn from this?

Hi guys,

after 6 good prints i finally have my first failure and clogged the nozzle :(((

The model i was printing was verified (already printed by many others), so no problem there. I set everything to be very quick: 0.3mm layer (with standard 0.4 nozzle), fast mode, no support. It printed well the (imho) most complicated part, then failed somewhere in the middle (i wasn't home), and now nozzle is partially clogged: it extrudes something but it makes weird noises..

Do you have any guess about what could have happened and how to avoid it in the future?

Thanks a lot

Here a pic of the fail and here the design i was printing.