Vibrato is a wonderful colour to add to your music - it can add warmth, tension and drama, or just bring out important and beautiful notes. However, it can also end up masking bad intonation, or becoming uncontrolled. So, it's very important to be conscious of where and how you use vibrato in your playing.
Make sure you practise completely without vibrato at times!
Firstly, take care that your vibrato isn't masking intonation issues. Make sure you practise your scales and arpeggios without vibrato so you can hear they are perfectly in tune. Then practise with vibrato, and see if you can get a consistent vibrato on every note. Can you keep the vibrato moving through the change of notes?
Next, let's look at how you use vibrato in your pieces. Try and play your piece with no vibrato at all. This might show up some intonation issues you hadn't noticed before. It might also show up areas where you have used vibrato to cover technical issues without realising. Try to keep the music expressive by using other techniques such as bow variation.
When you can play your music beautifully without vibrato, now is the time to start adding some. You should now be able to add vibrato consciously and to colour specific notes, rather than in an uncontrolled way on every note. If used a little more sparingly, it can create really poignant moments throughout your performance.