"Keep It Simple, Stupid." In this context, "keeping it simple" means keeping your goals and expectations realistic. Do not expect to be a virtuoso by the end of the first week. Instead, aim for something more attainable, like being able to play a scale at a certain tempo. If that sounds like a cop-out to you, then what's the harm in trying to achieve it? If the goal you set one day or one week is too easy, you can always make the next one harder.
2. Watch Your Back
Proper posture is important to getting the best possible sound out of your violin. When you are just starting, make sure that you are sitting (or standing) straight, with your feet flat on the floor. Reinforcing good habits now makes them second nature later.
3. Mixed Tape
Pick a time when your violin is in tune and take a few minutes to tape the neck (with brightly-colored tape that you can see from an arm's length) at appropriate places on the neck to help you learn where to put your fingers. You should be putting your fingers down in uniform places on each string to get the correct notes (if you're not, something's out of tune), so one piece of tape will work for all four strings. Be absolutely sure that your tape is in the right place! It would be good to double-check using a keyboard, if at all possible. This will provide a useful visual until your fingers' muscle memory and your own musical ear kick in, at which point you can remove the tape.
4. Check Your Bow
You can adjust how tight or loose the hairs of your bow are by using the screw at the "handle" end of the bow. For the best sound, it should be at a tension where you can comfortably fit your pinky or a pencil in the middle of the bow while you're playing. (You can also determine this by checking the wood part of the bow: it should be at a slight arc, not too straight and not too curved.) Also, make sure you use the right amount of rosin. Too much and the quality of your sound sill increase; too little and you have no sound at all. Again, with time, you will develop a good intuitive sense about these factors, but in the beginning you need to be more mindful of them.
5. Stay Positive
Your bow should always form a "plus sign" as you draw it across the string. Keeping a careful eye on the angle of the bow when you're first starting will get you accustomed to how your arm and bow hand should feel on each string.
6. Keep the Faith
Do not worry if learning the violin seems, at first, task of Herculean impossibility. As long as you take these tips to heart (and remain diligent with your daily practicing), you will see improvement sooner than you think!