Here is some basic information about taking good care of your instrument.
Your violin is delicate and sensitive to variations in temperature and humidity. When you are not playing your instrument, it should be kept in a hard case, out of direct sunlight, and out of cold drafts. It is also inadvisable to leave your violin in a car for extended periods of time. The reason for all of this is that variations in temperature can cause cracks in the wood or blisters in the varnish that would require repair.
The varnish on the violin’s body is vulnerable to the oils and sweat on your hands, so to protect the instrument's shiny finish, it is a good idea to handle it by the neck as much as possible and make a habit of washing your hands before you play. Equally detrimental to the finish is allowing rosin dust to build up. After each time you play, clean the dust off the strings, fingerboard, and body with a soft cloth. If you find fingerprints on your violin, you can use a slightly damp cloth to wipe them off. If your varnish becomes really dull in places, it is best to take your violin to a luthier so they can clean and polish it for you, or get their recommendation for one you can use yourself. Violin cleaners are readily available, but if you are concerned about maintaining the value of your instrument, defer to the professionals before using any.
Your bow is strung with horse hair, which has microscopic barbs all over each strand. These barbs are responsible in part for the friction that produces sound when you draw your bow across the strings. That being the case, the oil and sweat on your hands will ruin the hair if you touch it so try not to.
When you are preparing to play, tighten the hair enough so that it is not touching the wood, but not so tight that you lose the concave curve of the bow. You will need to regularly apply rosin, but probably not every time you play. You should apply enough for your bow to easily grip the string and not feel slippery, but if you are creating clouds of rosin dust you have used too much. When you are finished playing loosen the bow hair before storing it.