Violin position and posture can be a little bit awkward at first. And to be honest, it is part of what makes playing the violin a challenge! The instrument does have a fairly steep learning curve because of little road bumps like this. But there are a number of good ways of short cutting through the confusion and getting to know correct violin position quickly and without practicing 5 hours a day. Here are some good guidelines to get your started playing violin with good position.
When you first go to play a note on the violin, you want to make sure that you are meeting a handful of very specific guidelines. These can change to a certain degree depending on what notes you are playing or what kind of angle you are attacking the violin from, whether it be with a staccato, spiccato, legato or ricochet bow stroke. Just keep in mind that these are only guidelines for basic playing with a standard issue violin bow stroke and nothing more.
Start with the bow at a clean 90 degree angle with the string. This is very, very important because of the way the bow runs along the string. The bow running parallel to the string simply causes chafing with the steel twine and will produce a very poor sound. Even if the violin string is just a little bit parallel to the bow, this can still cause problems. Be sure to eliminate this or you will get stung for it later on.
Your elbow should have a clean 90 degree angle as well, and the wrist should be straight. This obviously assumes that you are starting the note by playing at the middle of the bow, but we can safely do that for a lot of notes without limiting our ability to play them, in particular short notes. As the bow moves up and down, the angle of the elbow and the wrist should adjust accordingly, but the bow should never leave the 90 degree angle with the string no matter what violin position you are in. This will keep your sound and violin intonation clean.
And be sure to keep your left wrist straight as well. A lot of players will skew their violin position by drawing the wrist in close to the fingerboard and bending it backwards in order to get a close hold on the notes. This may feel a bit more comfortable, but all it really does is make it extremely difficult to shift. When you try to shift, your wrist and base of your palm will strike the body of the instrument, making it much more difficult to effectively shift and create smooth notes. So keep that left wrist straight, no matter what!