I would suggest purchasing a beginner level book and, temporarily, starting over from the beginning. Good options are the Suzuki Method Books and also perhaps my Song Book series, which you can view or purchase here: http://www.simplyviolin.com/page10/page10.html.
For "starting at the beginning" the most suitable book in the Simply Violin series would be: Sing. Play. Learn. 80 Favorite Songs for Violin. For Suzuki, Books One and Two.
All of these books are also available at Amazon.com.
Starting at the beginning entails perfecting songs/pieces that you can play without difficulty and only advancing to the next song when the current one sounds exactly the way that you want it to sound. Since books like Sing. Play Learn and the Suzuki books are arranged in the order of increasing difficulty, you should be able to make progress through playing songs that are easy enough for you that you can focus on the basics. Playing music that is too hard is one of the biggest reasons for lack of progress.
I would suggest that you practice slowly and pay particular attention to bow placement on the string. Make sure you are drawing a straight and even bow and lead with the wrist. Make sure that you are not squeezing the neck of the violin with your left thumb. If you are having trouble finding the notes in first position I recommend using a product called First Frets. First Frets applies to your fingerboard and will show you the notes in home position. I have a local violin shop that carries them and I'd be happy to give you their information if you have difficulty finding this product.
Another good idea is to listen to recordings of great violinists, such as Perlman and Heifetz and to watch them on Youtube if you can absorb some of their technique that way.
Don't get frustrated if you don't sound good right from the start.
One thought would be to take a lesson even once a month or once every couple of months if possible. It is often difficult for students to see themselves and sometimes it takes a teacher to diagnose certain issues.
Best of luck to you.
