Being honest, most garage bands start out when a small group of people pools their possessions together and sees what they end up with - one drummer, two guitarists and a lead vocalist.
But if you were putting together a band from scratch - the ideal band of three to five people - what instruments would you include?
Here are a few suggestions:
For three people
With three people, you'll definitely need at least a drum set, but after that, is it really necessary to have a guitar? After all, the bass guitar is incredibly important for laying down the lowest pitches, but you can make up for it with a synthesizer. After you have a drum kit, you'll need a couple of things: at least one instrument with a lot of potential range, like a piano or a synthesizer, and a good lead instrument like a guitar.
For four people
One more person means a little more freedom. You'll still want your drum kit, but you can now add the bass guitar along with the lead guitar, and an optional fourth instrument.
The synthesizer is great these days, as you can stretch the sounds out to fit a wide array of songs, but you can also add another guitar - which is essentially how The Beatles were comprised. Not a bad way to create your own band.
A four-person band also means you can get a little funky; for example, ditch the drums and become an a capella group.
This might not suit what you're looking for, but it's something to keep in mind.
or five people
This may be crossing into "boy band" territory, but with five people, there's a lot of room for handling different instruments. You can even have a vocalist who only handles vocals.
With the five-person band, make sure to include drums, at least one guitar, at least one bass, and at least one keyboard player.
If those are the only instruments you need, you can add a lead singer and you'll have a complete band.
Obviously, these guidelines aren't very strict. You're free to start whatever kind of band you want, whether you want to bang on trash cans or have two sets of drums.
The important thing is that you find instruments with versatility; or at least band members with the same.