Boston Herald

A wise editor once told me: Always show up for the opening band. Why? Because you often find your new favorite in a support slot for your old favorite.

That advice suits the Outside the Box festival perfectly.

Philanthropist Ted Cutler’s gift to Boston (and thousands of tourists), Outside the Box is a fun, free event that hosts dozens of musical acts and theater troupes on five stages­ on Boston Common. From today through Sunday, the fest will fill undercards with some of the coolest up-and-coming acts in the world (but my picks all come from right here in Massachusetts).

With so much action, I thought you might need a little help finding the best stuff. My advice: Skip the headliners (Smash Mouth, Daughtry, Michael Franti) and go see these young aces.

Bearstronaut, today at 6 p.m., Fountain Stage — The coolest electronica act to come from our city since Passion Pit, which says a lot if you know the scene, Bearstronaut has finally released its debut LP, “Telecoast.” The record and the band’s live set will get you dancing (and thinking).

Ruby Rose Fox, today at 6 p.m., Capital One Stage — I won’t mince words: Ruby is a rock goddess hiding in plain sight. Soon this champion of old soul, modern indie and arty rock ’n’ roll will be making that Daughtry money. See her while she’s still free.

Dutch ReBelle, tomorrow at 8 p.m., Fountain Stage — Dutch ReBelle is in the middle of leaping two big hurdles (Boston MCs rarely go national; hip-hop remains a boys club). Give her a push into the mainstream by downloading “Whatchu Like” — a tasty blend of electro-pop and hip-hop.

Kana Dehara, tomorrow at 2:30 p.m., Tremont Tent — Kana Dehara was already a classical prodigy with a clear path to stardom in Japan when she discovered jazz. A Berklee scholarship brought her to Boston. The pianist has reinvented herself as a hard bop powerhouse.

Phunk Phenomenon, tomorrow at 2:30 p.m., Capital One Stage — Hip-hop dance with heart. This crew and studio strive to educate students while building self-esteem and mad pop ’n’ lock skillz.

Soft Cactus, tomorrow at 5:30 p.m., Lily Pad — Too often funk and soul bands grind down the edges, polishing off the point of the music. Soft Cactus retains those nice jagged corners and prickly bits by mixing in heavy guitar and indie energy.

What Time Is It, Mr. Fox?, tomorrow at 3:30 p.m., Tremont Tent — Crescent City soul, vaudeville and medieval music in one group? Sure, why not? With an aesthetic that’s both Brechtian and Winehouseian (as in Amy), this ever-evolving outfit blends genres with wit and charm.

Amy Kucharik and Friends With Benefits, Sunday at 3 p.m., Fountain Stage — Kucharik sings old-timey jazz. The trick is — wait, make that the tricks are — that these old-timey songs are originals done with Kucharik playing ukulele and her swinging friends backing her up on everything from washboard to upright bass.

Blak Madeen, Sunday at 2 p.m., The Platform — Politically charged hip-hop in the best possible ways (insightful, original and progressive), this Boston duo has hit its stride at the right time. At a time when too many Americans have pigeonholed the Muslim faith, MCs Yusuf Abdul Mateen and Al-J destroy preconceived notions.

Opera on Tap, Sunday at 6 p.m., Lily Pad — This local group of singers brings opera, show tunes and jazz standards to parks, galleries, restaurants and neighborhood pubs. For those who think opera belongs in Vienna, this band grounds the great art form in visceral, minimalist performances — although sometimes they get fancy and wear those obligatory Viking helmets.

SambaViva, Sunday at 2:30 p.m., The Grass — Skip the Olympic games and get some real Brazilian culture right here. SambaViva is dedicated to authentic dance grooves from Rio de Janeiro to Rio Grande do Sul to Rio Charles.

The Valerie Stephens Group, Sunday at 6:15 p.m., Fountain Stage — Stephens leads a tribute to musical icon Nina Simone with a voice that can handle the storied catalog.