The easiest way is by air. Many but by no means all of these are with Adria Airways, the Slovenian national airline. Other participants report roughly comparable fares. From Austria, in fact, you can go directly to Bled without first going to Ljubljana. Some Bled veterans have rented cars in neighboring countries and driven to Bled.
Buses are generally clean, punctual, and cheap.
The distances in Slovenia are short enough that both kinds of bus make the run to Bled. There's a small extra charge for checked luggage. From Kranj, catch the bus to Bled. From Kranj, catch the bus to Bled. I'm not sure how often buses run from Kranj to Bled, but I think it's at least once an hour and probably more often.