Pack light and make sure to bring bathing suits and towels if you're planning on swimming. Bring cash with you too, as some of the activities are cash only.
The lake will be busier during the summer months, so be prepared to wait a bit for a bit for boat rentals during particularly crowded times.
Although you can explore Lake Bled year-round, this itinerary is probably best for families visiting the area outside of the snowy season. That way, you can fully enjoy all of the activities that Lake Bled has to offer without winter weather getting in the way!
If you're looking to save a bit of money on this adventure, you can forgo buying tickets at the church and castle and simply enjoy their beauty from the outside!