I've only been playing violin a little less than 3 weeks today, but I do play other instruments, so I'll try offering a tip here.

Take any piece of music you want to learn and find the beat on a metronome that is about right for it.  Try playing it.  If you can't, or if some parts are difficult, then slow down the metronome a bit at a time until you find a tempo that you can do the piece perfectly at, every time. Slow it down enough that it feels like child's-play to do the piece or section you are currently working on.

Stay at that tempo for a day or two, working on getting the feel of the piece and letting your fingers learn how to move.  When the piece feels easy and like it is second nature to you, start taking the beat up a little at a time every few days.  If you can do everything perfect at that tempo, then that is your new practice tempo.  But if you mess up any bits or some parts even feel hard, then slow it back down for a few days.

You want to do this because it does not help to practice making mistakes.  If we practice mistakes, then we keep making mistakes.  If we practice perfection, then we get good.  Take any piece as slow as you have to, so long as you play perfectly at that speed. 

Speed comes easy.  Anyone can play faster with very little work, but if you focus instead on getting everything just right, the speed will come naturally a bit at a time.