From Milano Airport one can get to Lago di Garda: Airport - Milano Centrale (main train station) by shuttle bus, around 5 euros one way. Buy the ticket from the driver who stands on outside the bus at the door...
Shuttle buses leaves every 30mins, if not every 15mins but very often anyway.
Milano Centrale take train to Desenzano sul Garda and you will reach the south end of the lake within 1.30 hours.
Remember to stamp your ticket before entering to platform!
If anyone discover a better way of going from Malpensa to Lake Garda please share your info with me. ;-) Thanks!
As moust of the north side of the Garda Lake, reach Limone by boat its a great idea. The service during the summer season has a big frequency. You can catch a boat almoust every 20 minutes and you dont have to worry about finding a parking for your car. Ticket start with Euro 1,90 and will increase according the distance you make. Its possible, and smart, to buy a day ticket for the north side of the lake. Cost about Euro 12,00 per day. time tables and full prices you can find on the website of Navigarda.
To get around Garda, probably the easiest (and coolest?) way is by "connection boat". They go from South to North and from western to east coast.
Buy your ticket at the harbour before entering omboard.
Check out the towns and timetables from the link below.