In a slight twist from past years, American Idol allowed Hollywood contestants to play instruments while singing.

I know. What a novel idea.

However, as a pianist of 34 years, it's easier said than done, and I'm actually pretty damned good at it. On Tuesday night, Idol musicians made some classic mistakes, and I thought it would be a terrific opportunity to outline, specifically, how to be the best accompanist possible. Well, at least on the piano.

1. Don't overshadow the primary instrument, whether it be a vocal or a trumpet. What you play should be virtually invisible but just enough to provide the perfect landscape for the vocalist.

2. Don't stray from the basics. One Idol contestant laid down some decent but sophomoric piano licks during a Billy Joel song, and Simon Cowell called him out on it.

Here's the God's honest truth. Unless you're a jazz or classical great, there is somebody better than you on the piano. If the point is to enhance vocals with instrumentation, then leave the runs at home. You'll look like an idiot.

3. Make sure you can actually play. This is going to come off as terribly cocky, so please forgive me, but I can actually play. Well, in fact. Most of these Idol kids could merely form chords, except for Brooke White, who did a darned nice job on Christina Aguilera's "Beautiful".

There is an art to playing in some semblance of an arrangement while a vocalist sings. One cannot merely play competent chords and notes. It has to sound right, complementary if you will, to the primary instrument.

Apparently, 7-year-old David Archuleta can play pretty well, as Simon complimented him heartily on everything tonight. While I kid about Archuleta's age, he does look like he's all of 10. But here's the thing: He can really, really, really -- you can't deny him -- sing. In fact, I am pretty sure he's the best young male singer the show has ever had.

However, with that said, he's going to face a mountain of abuse once he gets to the Final 12. And, believe me, that's where he's headed. He's got that Kevin Covais, Sanjaya, John Stevens young kid vibe going for him. And, we live in a brutal world, well, in terms of criticism and people who have no other intention but to poke fun.

But I digress.

Probably the most important part about being an instrumentalist for somebody else singing is in leading them through the song and helping them to mask mistakes. Not that we pianists never err, but our job is to make the vocalist shine.

If he or she misses a verse, play an extra measure and lead them into it.

If he or she changes chords on the fly, you had better be ready to do so.

If he or she passes out on stage from drinking too much 40-year-old Scotch, you the pianist had best be ready to play awhile or at least call a cab.

This stuff is not rocket science, and most of you musicians will think this entire discussion is patronizing. However, very few young musicians know even how to accompany themselves, and Tuesday night's episode of Idol underscored it.

As far as the Top 24 and who will get picked, here's what I would say: David Archuleta, Carly Smithson, Michael Johns, Danny Noriega and Asia'h Epperson were really, really good.

If they're not all in the Top 24, I'll be stunned.

Given that we've had a few weeks to ruminate over this season's crop of singers, I'd also say that my pre-Top 24 favorites to go all the way, believe it or not, include the young Archuleta and the tattooed Smithson.

What's amazing to me is that Smithson (nee Hennessy) was such a bomb at MCA back in 2001, losing like $2.2M for the company and selling only 3 CDs (or something equally as ridiculous). She can flat out sing. She's got a unique look and what seems to be an incredibly grounded personality.

Alas, we have plenty of time for this discussion later, and it would probably be best if I save it for my American Idol site. But the whole playing-instruments tangent allowed me the chance to review some musician basics.

If you're a musician and have anything else to add to my list, feel free to comment below or post your own blog entry and link to this one. Ciao.