That's about all there is to it. The other rule; never associate yourself with anything negative. Like even if your last employer (or near-employment experience) was a complete dick, if you're asked "how did you get along with the people at your last job" or something like that, the answer is always "great". If you're asked about your "least favorite X" or "worst X experience", it's a trick question. ANd...uh....be able to say you've washed dogs? Sometimes they ask corny stuff like your favorite book and why, or how would you spend one wish, etc, but for a retail job, I don't know if they'd want that much information.
Yup, most decent places will have a receptionist and a waiting room, but at Petsmart you'll need to nab a clerk to hunt him down, and to be honest you'll be lucky if he remembers your interview. Just be sure of yourself and act confident "Yes, we arranged on the phone to meet today." There's a 50 percent chance he'll do something absurdly rude like ask you to come back in an hour or reschedule for a different day, in which case you can either assure him it won't take long and you'd like to talk now if possible because your'e serious about the job, or suck it up and reschedule. Just keep in mind he's the one being rude and you're too good for his establishment, but you're sucking it up cause it's your first job and if your manager didn't suck you'd have no first-job stories to tell your friends.
Aw hehe. He may be perfectly fine. I've just had a lot of friends have ... turbulent experiences with retail management. The people at ACME forgot my sister's interview 4 times, and sent her away all four. Then when they let her in, they asked if she had a drug test yet, and when she said no, they said they couldn't count her application. My first job was teaching horseback riding at a camp, and the interview went so smoothly that I didn't know what hit me when they gyped me out of $150 of my pay at the end of the camp because of a technicality in my contract I so gleefully signed. Basically....employers can be pricks, and a lot of them are out to take advantage of unexperienced workers who don't know any better.
I quit my first job last june. My employer was so bummed she quit. XD Just kidding, I quit the same time the old manager did. She quit just because, I quit because I was going overseas.