Temperature and humidity:
Stringed instruments are happiest given a constant temperature of 60 to 70 degrees
and a relative humidity of 35 to 50 percent.

Wood is hygroscopic - it attracts and absorbs moisture from the atmosphere.
Moisture makes it swell.
Different kinds and cuts of wood shrink and swell at different rates.
Hence loose pegs with humidity changes.
If your home or studio falls below about 20 percent humidity, consider using a room humidifier. 
Overhumidifying is worse than not humidifying at all.
Tom Sparks, who teaches violin making at Indiana University, says,
"wrapping your instrument in silk or tightly woven cotton slows the transfer of humidity.

During winter months with low humidity I take my case into the bathroom
when I'm taking a shower every so often.

Normal Maintenance:
After playing the violin, gently clean it with a soft, clean, lint-free cloth to
remove rosin build-up on the strings and any dust, oil or sweat on your instrument,
including the chinrest.

Polish is rarely needed, and when necessary, only a commercial violin polish should be used. 

Loosen the hair on your bow before putting it back in the case.

Repair:
Never use commercial glue to repair cracks on your violin.
Instrument makers use a special glue for violin seams and repairs.

Sticking or Loose Violin Pegs:
Peg compound will lubricate the peg and provide enough friction so it will not slip.
When using peg compound or any other product to help with sticking or loose pegs,
use it sparingly because a residue can build up over time (some violinists avoid these products).