Learning through trial and error is invaluable. Unless, of course, you’re making the kind of mistakes that cost loot. There are small, cheap-o lessons (don’t buy falafel at General Tsing’s Kitchen). And then there are bigger, spendy ones (you wouldn’t own those denim pedal-pushers if it weren’t for the wine spritzers with lunch). So although you’ll probably keep ordering omelets at late-night steak joints, The Blues Jean Bar in Santa Monica will keep your denim follies in check. The new store wants you to try, try, and try again, until you find the right pair. They carry twenty lines for ladies — staples like AG, Joe’s, and People’s Liberation, as well as exceptional finds like Sacred (Sacred Blue’s new high-end line), 1921, 575 Denim, and Posh’s line for Rock and Republic. Guys and kids can get new jeans, too, from Seven for All Mankind and Paper Denim. Score something for your top half from C&C, Acrobat, and California Vintage. Tonight, doors stay open until 9 p.m. for the annual Montana Avenue Holiday Walk. And every Friday, they host happy hour from 4 to 6:30 p.m. Swing by, enjoy cocktails (and discounts), and hunt for your new favorite jeans. Not necessarily in that order. The Blues Jean Bar, 1409 Montana Avenue, at 14th Street, Santa Monica (310-656-7898 or thebluesjeanbar.com).