When you queue up to pay the toll, not only you must avoid the yellow-marked "Telepass" lane, but also the lanes for "Viacard" only. Viacard is a prepaid card.
Stick to the lanes marked for cash payments (the sign has a logo with banknotes and coins). However if you end up in a viacard only lane it's not too bad, because there you can pay with you credit card.
There is no general rule to where are the different telepass/viacard lanes, sometimes on the left, sometimes on the right, just follow the signs for cash payment.
In some parts of motorway (for instance around Milano) you must pay before you enter, in this case you will not receive a ticket at the toll booth but you'll be asked for a couple of €.
Be more careful than usual while driving in Italy.
The general limit on the motorway is 130 km/h. Nobody goes so slow in Italy except huge lorries and swiss pensioners
The law allows the motorways with three lanes to have 150 km/h limit, but afaik no motorway manager dared to increase the limit to 150 yet.
In case of rain the limit drops to 110, and in case of fog it's 50 km/h on all the roads (including motorway).