For my younger (still-growing) students, I typically recommend that parents rent the fractional size instruments, as most music shops offer an option to trade in the instrument for a larger one as the child grows. Alexandria Music Company offers a great rental program. (Full disclosure: I teach there.) Once a student is ready for a full-size violin, the best option is to purchase a nice-sounding fiddle rather than rent. In the DC area, we are fortunate to have several wonderful shops with great sounding instruments at reasonable prices. Brobst Violin Shop, Foxes Music, Lashof Violins, and Potter Violin Company, and Day Violins all offer an excellent selection. Trying and buying a violin, viola or cello is something that must be done in person and not over the internet. The player needs to experience the sound and feel of each instrument, because they all feel different! Visit one of these locally owned shops if you are in the market for a rental or purchase!
I'm sure everyone who has played music has experienced this: You're working your way through a new piece of music. You struggle to stay in the key signature, trying to remember the correct articulations and fingerings. Meanwhile, you may be completely disregarding the rhythm, thinking: "Ah, I'll get to that later." Occasionally my students will admit to me that they're not counting. And I have not-so-fond memories of myself as a young student learning a piece, merely "guestimating" the rhythm. Eek! Stop! Put down your instrument.
Times like these are a perfect opportunity to pull out the metronome. Turn it on, setting it on a nice slow tempo. Set it at half the normal tempo, if you need to. Sometimes it helps to set the instrument aside and simply clap out the rhythm of the music with the metronome on. Try speaking the rhythm (i.e. "1-e-and-a 2-and...), and make sure you know exactly how long or short each note is.
Any basic metronome will work. Most run around $20-30. If you can afford it, the Dr. Beat (DB-90) is the current grandfather of all metronomes -- it actually counts out loud for you in a human-sounding voice. If you happen to practice near a computer (and it has nice loud speakers), you can use an online metronome.
A lot of the time, students who only play music by themselves tend to let their rhythm and counting go by the wayside. That makes it extra-difficult when you attempt to play in an ensemble or with an accompanist! Spend some time with the metronome. It may be frustrating at first, but you (and your teacher) will be glad you did.
Over my 20-plus years of string playing, I have had the opportunity to try quite a few different varieties of violin strings, and have found that some are better (much better) than others. Violinist.com offers an excellent breakdown on types of strings. As the article mentions, string preferences can vary by player and instrument, so it's really best to try out some different types on your own. From my experience, my personal favorites are...(drum roll)...Evah Pirazzi strings. Usually coming in at about $70.00 per set, they're a bit expensive, yes. But I've found them to have an unusually rich sound that really improves the tone of my instrument. The only downside is that the beautifully rich sound does not last forever, and they can begin to sound dull after a few months. For students or intermediate players, I find that Dominant strings have a nice warm sound, are durable, and are fairly reasonably priced.
While it can be fun to experiment with different varieties of strings, it's important to remember that quality, mindful practice is the surest way to a beautiful sound. Lovely-sounding strings are just the icing on the cake.