Greater sound can motivate a beginner to practice more. I'm not saying that you, beginners out there, should get a better, expensive gear in order to motivate yourself, but the most basic thing that you can do when going to purchase an amp is to get an amp that has reverb in it. A reverb is all it takes to shape your tone beautifully when starting out.
Usually, a practice amp has about 5 knobs or lesser, depending on what type of amp that you have. They are: Volume, Bass, Mid, Treble, Reverb
Let's look at all the individual knobs:
Volume: This is to adjust the sound to make it sound louder or softer.
Bass: To adjust the low frequency sound
Mid: To adjust the clarity of the sound
Treble: To adjust the high frequency sound
Reverb (sometimes in an on/off button instead of knob) : Reverb is a feature that lets your guitar sound like you are playing in a hall.. So the reverb knob adjusts the 'hall sound'
So how to set a better tone? Depends. I usually set everything to neutral zone. You have to check your own amp first. If let's say your knobs max level is 10, then i would put it at 5.
For the Mid knob, some like more clarity while others like their sound to be dirty. So if you want a more dirtier sound, lower down your mids to say, level 3 or so.