Ah, punk! Some say it's enough to pick a guitar, an amp, a jack, and a strap (the longer the better), crank it all up and it should sound like it's meant to.
But when we talk about the historical English punk or the current US punk rock, it is easy to realize that their sound was far from being dirty.
Did you say garage?
Mick & Steve Jones didn't play just any guitar, they played superb Les Pauls. The guitarist of The Clash used a Mesa Boogie, and legend has it that the guitarist of Sex Pistols added a Big Muff to his Twin Reverb.
The Offspring, Blink 182 and all other similar bands have the same luxurious taste: Mesa Boogie, Orange and some other very expensive tube amps.
By now you have surely understood that it won't be easy to get a badass sound with your starter kit.
On your guitar crank everything all the way up, select the bridge pickup and you're ready to rock 'n' roll, baby! However, if you crank up your amp you may find the sound of the clean channel too neat and the sound of the distortion channel too hardcore.
Decrease the gain of the distortion channel, halfway for example, and shape your sound with the EQ. Boosting the mids will give you a very classic sound, and the highs will dirty up everything. Finally, reducing the lows will estrange you from the metal world.
If you are lucky enough to have an amp with a contour, shape or blend control, they can come in very handy: they are the ones that change the color of your sound, specially the mids. It's up to you to find the proper dosage.
If in spite all the above you still can't find THE sound (which is usually the case if your amp doesn't have mids controls), you will need to add a small magic box to your arsenal.
Effects to play punk?
Rest assured, we aren't talking about complex pedalboards here.
Every pedal called simply "distortion" is, in theory, capable of producing an interesting result. If you are a Mohawk punk, the Boss DS-1 or the MXR Distortion + are the standard and they are very easy to use. However, guitarists from the "American Pie" generation may find this sound too coarse. In that case, you might want to turn to more modern distortions like the Ibanez Slam Punk, Digitech's Grunge, or even to pedals aimed for metal, considering that the California punk sound isn't too far from it.
And if despite all this you are still not fully convinced, you might need to take a better look at your instrument. Maybe you are not getting the sound you are looking for due to the pickup type: a single-coil produces a more brilliant and biting sound than a humbucker. Unfortunately, in such cases you will be forced to change at least the pickups, when not the whole instrument itself.