What does one need to know about playing old 78 rpm records?

They need a needle designed  for playing them.

Here ya go!

Do NOT attempt using your MC to play the 78s. 

Virtually all pre-WWII 78's (and some after) were made with shellac resins, so don't use any alcohol for cleaning.

Be sure to follow the manufacturers recommended tracking force on your made-for-78 cartridge to avoid stylus and record wear and prevent skips and distortion.

Before the mid-1920's, the actual speed of these recordings was not standardized and varied among manufacturers, so a turntable with pitch control is a plus. The mid-20's also marked the beginning of electronic recording, using amplifiers to drive the lathe. The sound improvement was dramatic.

If you want to venture farther into the world of 78rpm, there are specialized phono preamps that allow adjustment for the many varying equalization curves used.

If you are fortunate enough to find lightly played recordings, you will be surprised by how good some of them sound.

A sincere 'thank you' to all respondents! This is truly a place with an abundance of knowledge and it's greatly appreciated!

When my father died 25 years ago his 78 collection looked Mouthwatering .  There was Toscanini conducting Ravels Bolero, Ormandy and the Philadelphia Orchestra accompanying Rachmaninov in his Piano Concertos, and many others.  My Garrard tt had a 78 rpm setting and I picked up a separate tonearm fitted with a mono cart from a reputable dealer.  I tried cleaning the 78s-the dealer had a Keith Monks machine and charged by the record—but the roar of the surface noise rendered them unlistenable .  I have subsequently acquired digital restorations of these recordings, and many others, as well as attempting to make a few myself with some of the software availabie for this.  The professional restorations are nothing short of miraculous, with the enjoyment of listening to legendary recordings without the feel of sonic compromise.

  I wish the OP well, and I hope his father kept his collection in better condition that my father kept his, but if his main goal is the end product-a well restored recording to be enjoyed with a minimum of distraction-it’s amazing what current restoration technology can achieve 

see SP stylus

playing norally with Shibata stylus for instance. Simply change stylus to SH spherical, play 78