Essential Guitar Pedals
There are some things that just help you get a better tone...
And many of these things are pedals. Sure, your totally awesome, custom made Strat and $5,000 tube amp are where it starts, but good tone also has a lot to do with what comes in between those things to help shape your sound into... Well... Your own personal sound.
Things to keep in mind:
1) Don't knock a pedal just because everyone uses it. That's a good thing, because it's something you can count on. It probably won't sound the same for everyone too, so you can still shape it your own way (eg. An Equalizer).
But the inverse is also true: just because everyone uses it doesn't mean it's necessarily an awesome pedal (eg. The Boss DS-1).
2) Don't automatically cut out cheap pedals. Even Behringer has their hidden gems.
So here ya go, a checklist to be your first (or next) step into a pedalboard/rig in order of importance.
PIcture from EvanGodBold
THE MOST ESSENTIAL
I don't care if that new phaser with distortion, chorus and delay built in looks cool, if you don't have a tuner, then everything else can wait. Nothing will sound worse than a guitar that isn't tuned. A good tuner pedal will keep that from happening throughout the entire show, without forcing your audience to be subjected to loud guitar tuning. Since it can be used to cut off your signal, it's extremely useful when you're changing guitars.
It doesn't have to be expensive, just durable. My tuner of choice is a Snark stage tuner. Accurate and fast!
I personally use a Snark Stage Tuner because they are small, simple, and bright with a big display
Once you have a decent number of pedals, you definitely don't want to use battery power. You will save a TON of money by using a power source, even if it's just an AC adapter and a daisy chain. If you have (or are planning on getting) a lot of pedals, get a legitimate power "brick" that has multiple outputs so you can power all of your pedals with clean power, so you won't get any noise from your supply.
Power Sources Online
The standard AC Adapter for pedals, good for powering a few pedals.
What the pros use for their larger pedalboards. Good if you not only have numerous pedals, but also have pedals that use different voltages.
There's a reason why every track in the studio has equalization in it: it lets you accentuate the good in a signal and stop the bad. Equalizers are extremely helpful. If you have an amp that lacks in one area (eg. Your amp is excessively bright) or has a dull tone, or if you're just looking for something to thicken your sound a bit, stick this in your signal chain. It will take some tweaking, but you will discover frequencies that you didn't know your guitar had that will make your guitar that much bigger onstage.
An equalizer can make a crappy amp sound good, and a great amp sound terrible. Be wary of your use, and make sure your settings are beneficial. The more editable band frequencies, the more tweaking and more in-depth improvement.
ESSENTIAL IF YOU HAVE A LESS THAN DESIRABLE AMP
A Standard Equalizer
A much more in depth and tweakable equalizer with more editable frequencies
Face it: your guitar probably has a grounding issue. Ya know, it hums when you're not touching it. Most guitars have it. Or maybe you have single coils that hum, hum, hum a 60-cycle song all day long. You could deal with it... But if it doesn't drive your audience crazy first, it'll do it to you. It's so annoying! Thankfully that's why Noise Suppressors were created.
In addition to ending your 60-cycle blues, they also cut out other noise, such as hiss or hum other pedals may create (eg. a compressor). They can also help reduce crazy feedback, and usually can power other pedals. Altogether, pretty necessary to any professional player. Especially in a recording situation.
Shouldn't really be essential, but if you like sustain you'll love a compressor. A compressor will not only keep your guitar at a pretty consistent volume, but it will also accentuate your playing dynamics and increase your sustain DRAMATICALLY. Can also be used as a booster to some point. Generally a good idea, but not essential, especially if you use distortion which already compresses your signal.
The standard compressor/sustainer
The compressor many pros opt for
If you're in a band this may be helpful. A booster can do multiple things for you:
1) Overdrive your TUBE amp (not a solid state or digital).
2) Create a boost in volume for you to rise sonically over the rest of your band for a solo or something (a treble boost would help with this).
3) Some boosts have a mild built in distortion.
Not really essential, but nice to have.
Overdrive and distortion is really essential for most types of rock, and is used as an accent in many other kinds of music. Even if your style doesn't necessarily call for distortion, you can still use a light overdrive, such as a tube screamer, for a mid boost in leads, or to wring out a little bit more gain from your amp.
The standard overdrive, typically used in solos as a mid boost.
If your amp has crappy reverb, or doesn't have it at all, this pedal can be a great addition to your board, especially if you play reverb-heavy music. Reverb pedals also have a wider variety of uses than the reverbs that often come in amps; they can become more drastic in effect, can create modulated sounds, and some can even reverberate forever! They are also always a tap away, where some amps don't always allow for remote control of reverb.
If you have multiple rigs, or different amps, this pedal will be really useful, and pretty much essential. Until then you don't really need one unless you want a killswitch of some sort, though some can power other pedals.
Power Source Hum Eliminator
If you use a wall wart (AC Adapter) I'd say that this is fairly necessary. Noise can seep in through your power source and corrupt your clean signal. Usually power bricks already have power filtering built in so that you don't need one of these, but some wall warts are not filtered and may cause noise. In this case, this is necessary.
Power Source Filters Online
The First Real Effect...
The first real effect I would get for guitar would be delay. It really opens up a number of doors for you as a player, and can make your guitar thicker and more interesting. You will also learn many new ways of playing and get a better sense of rythum