The first thing you have to do is find somewhere you can practice. Your first option is to practice at one of your band members houses. This is the cheapest option that you have available, however there is the problem of your neighbours and the volume of noise you will be producing. If your neighbours, don’t mind then go right ahead, as this will save you a lot of money, and you can practice for as long as you want.
Your next option is to hire a practice room. The advantage of which is that you can make as much noise as you like, however it will cost you, normally between £5 and £20 per hour, but for this you get to use the house PA, microphones, stands, leads etc and you can also hire amps, drums etc for a small charge. You can search on Google to find rehearsal rooms in your area and to check the prices to find the cheapest solution.
When finding a rehearsal space it is always important to make sure that it is easily accessible to all band members, it is also important to make sure that all band members have transportation to wherever you are practicing.
Band practice should be held at least once per week. If you are paying to practice then you probably won’t be able to afford to practice more than this, however if you are practicing for free then there is no harm in practicing more than this, but I think that one three or four hour practice per week should be fine.
The best thing to do is to make a specific time and day for practice, 5pm to 9pm on Sunday for example, and stick to it, make it your practice day, and make sure that everyone in the band knows that at this time on this day to be at the rehearsal room ready to play.
I have found from my experience that this system is more reliable, because everyone knows that you are practicing and will therefore not arrange to do anything at that time, whereas if you don’t have a specified practice time and just ring everyone up on the day you are due to practice and tell them to get there, the chances are that someone will be doing something else and practice will have to be cancelled.
When setting up you gear to practice it is best to set everything up as if you are playing a real gig. Look at the image below, you can see that the amps and PA speakers are set up slightly behind the drum kit. Setting up your equipment in this way means that the drummer will be able to hear what everyone else is playing a lot better, this is important, because the drums are so load that if you position the amps in front of the kit the drummer will have a hard time hearing everything.


