* Going out during lectures
Usually students go out just at weekends. You can go out from Thusday to Saturday in order to get good fun.
Salamanca is full of good places to out at, so it is really a problem to advise about this question. If you go out on Thuesday, you may go to bars with special offers (parties, second shot free,...) and to finish in a disco.
If you go out on Friday or Saturday you will find almost everyplace full of people so going to one place or another is a personal selection. In some places on friday you can get second drinks free (e.g. Pino).
If you like rock, punk (similar stuff), i can give you some good places: La Iguana, Paniagua, Chao, and Rivendel. And to finish of course El Potenkim, and later (after 6:00 a.m.) El Contrastes (this is a place we don't like at all because it is too small for the amount of people that go there). If you like other kind of music then you will have to discover the places you like by yourself.

* Going out in Summer
In summer there are fewer people, but there are more foreigners. And foreigners like to go out every night. Their typical planes they frequent are Camelot, Puerto de Chus, Submarino, Moderno, Cum-Laude, El Sol. The most popular meeting point is "the Litro Bar" (not its actual name) where can been found on the corner close to Morgana.
As a foreign student you can take advantage of lots of cheap of drinks, (not always goodquality) parties and promotion night.
For summers, discounts are available, eg. El Helmántico. Another interesting thing in summer in Salamanca (and Spain in general) are the large number of fairs. In August in the towns around Salamanca there are a lots of fairs. Salamanca fair start on the 8th of September and finish on the 21st.