A musician can never practice too much. The problem is, you are not usually inclined to.... There are a number of reasons, one can be a lack of suitable space to practice. If every time you want to practice some one else has to accommodate you, you can get a subconscious urge not to bother them. This combined with laziness and lack of discipline will lead to long spells of no practice. Not good.
This is the space in which I practice, also known as my room. I had several options to choose from, but only this one is heated.....The Kentucky K150 mandolin on the couch is a good entry level model. I bought this so I could teach a mandolin student, and have picked up some mandolin in the process. I also keep a banjo and guitar in here, just for practicing.
I share this room with a younger brother, which is an issue with nice instruments and equipment. I have told him in no uncertain terms that touching any of this stuff means big trouble. The risk is worth it though, no one is bothered when I practice up here.
Here you can see one of the nicest tools for a practice space to have. A $90 portable DVD player - for instructional videos, as well as CDs. This makes a lot of equipment unnecessary - no external speakers, TV, CD player, etc. It can even run off batteries for a while. Instantly turns any room into a practice area.
Here we have the most compact and easy to use virtual strobe tuner I have found. The lights go around in a circle, clockwise is sharp and counterclockwise is flat. The faster it goes, the further off you are. THe trouble with strobe tuners is their precision and lightning speed can be hard to interpret. That is the problem with the Petersen tuners (which are also very accurate); the display is a pattern of squares scrolling up or down...which is it, up or down? It can be hard to tell. This one is very bright and easy to read; batteries last awhile, but the power button is very easy to trigger so don't shove it into a bag or you may run the battery down.
A good chair and a guitar stand, definite must-have. The guitar was my grandfathers, an old American-made Epiphone with a deep ringing woody tone. I keep it here just for practicing, the CA guitar goes with me on the road.
Inspiration comes from many places; here is one of them on my wall. This is a newspaper clipping from our first jam camp with Pete Wernick "Dr Banjo", at the Merlefest music festival in Wilkesboro, NC. We have attended all but one of the camps since 2003, and now we are setting these up all over the country with many different teachers. The clipping is faded now, but still serves as a reminder of where I've been.
Here's the view out my window. Not a necessity for practicing, but it lights the room quite well, and is nice to look out on while you are playing scales or boring exercises.
As a practice space, it works pretty well for me. I keep a log of the hours spent, and I am able to keep at it for an hour every day.