So, let's start with the easiest rules to follow so as not to suck:
Rule No. 1: Don't make rap music.
If I want someone to talk to me about how rich they are and about how bitches be all up ons -- all while some annoying, repetitive beat plays in the background -- then sure, I'll go ahead and tune in to a rap station. No, your lyrics are not fresh, and no, you do not have musical talent. And there's a reason why everyone's favorite part of songs like Eminem's "Sing for the Moment" is the part sampled out of an actually good song.
Rule No. 2: Don't make country music.
Country music is in an entirely different realm than rap music -- I actually respect the musicianship of a lot of country music. These guys and gals often actually can sing, and they usually can play instruments, to boot. So, why is this a rule to prevent suckage? Because country music is annoying as fuck. Not to sound cliché, but I truly don't give even half a fuck about your pickup truck, your dog, or how your wife done left you. And unless you came to play a concert fresh off of a cattle drive, leave your dumb little cowboy hat at home -- you're not a cowboy.
Special Exception: You're allowed to be Shania Twain or Taylor Swift and not suck. Yes, I realize that publicly posting this exception causes immediate revocation of my Man Card. Truth be told, I have a feeling it was revoked years ago when I sang "That Don't Impress Me Much" at karaoke and fuckin' rocked the house. Yes, that happened.
Rule No. 3: Don't suck live.
If you suck live, it pretty much means you just suck.
In most scenarios, this means that you really just aren't very good at what you do, and it takes the magic of multiple takes over weeks or months in the studio, as well as auto-tuning and other production tricks to get you to sound halfway decent. Truly good musicians record something that sounds great, and then they practice and practice and sound just as awesome when they get on stage. Why does Ashlee Simpson have to lip-sync when performing live? Because she sucks. Why does Muse refuse ever to lip-sync or pretend to play instruments when playing live? Because they're music gods and incredible musicians.
Muse is so awesome that when they were told at the last minute by an Italian talk show that they had to lip sync, they decided to make it incredibly obvious by switching instruments and "playing" so horribly that they couldn't be taken seriously. The people hosting the show knew so little about Muse that they had no idea anything was awry. Pay particularly close attention to lead singer/guitarist Matt Bellamy as he rocks out on the drums one-handed at one point. (The drummer is "singing and playing bass," while the bassist is "playing guitar and keyboard.")
You also can suck live simply because you have too much faith in your jamming skill and how much people give a shit about said skills. Exhibit A: The Mars Volta. They're pretty amazing on albums, and they just throw a bunch of experimental shit in there and jam out to perfection in the studio, making like 10-minute-long songs that are generally enjoyable for the most part. Then they get on stage and think, "People obviously love it when we just go apeshit and jam. Let's take that to a level that no one wants! We're awesome!!" So they randomly pluck strings, flail on drums, and grunt into the microphone in the middle of songs and it simply sounds like a cacophony. No, it isn't good when you randomly rock out and jam. Plan that shit out so my ears don't bleed. Kthanks.
Exhibit B: The Dave Matthews Band. I went to a concert and it was excellent until about 45 minutes in when a song decided that it wasn't going to end. They had about 30 minutes or so left to play, and they decided to fill that entire period up with a bunch of instrumental solos instead of playing more songs that we wanted to hear. Excellent choice, douchebags. The violin player would move to the center of the stage and rock out for 2-5 hours, and I envisioned him thinking to himself the entire time, "YEAH! Violin! Vi-oh-fucking-lin!" Then came the drummer, and he was all, "Drums! Drums! Drums! YEAH! Drums! Drums! Drums! YEEEEAH!" How about -- no. Just end your song and play another one we want to hear, idiots. Stop catering to all of the high people in your audience who aren't noticing how much time you're wasting.
(UPDATE: Duh, a large majority of DMB concert-goers are high. Catering to the majority is a good business plan. My hat's off to you, DMB.)
Note: Rule No. 3 also works in reverse. If your album isn't that great, but you put on a great show, I'll actually enjoy your album more next time I hear it.
Obviously there are plenty more rules I have in mind, but let's let these marinate for a while before I come back for part 2. These are pretty good starting points, though.
Oh, wait, there's one more really easy one:
Rule No. 4: Don't be Nickelback.
That's the entire rule, really. Kinda speaks for itself.
But you know what? Here are some examples of why, anyway:
1) Listen to this MP3 with headphones. The two first Nickelback singles played one out of each headphone. They're the exact same length and have the exact same song composition. Pretty sad.
2) Here's Nickelback having rocks thrown at them at a concert for sucking too badly: