In 8 words or less...

[AQUANOVA]

Practice slowly to play fastly.

 

[DanGroove]

Learn effective muting - floating thumb

 

[noeinstein]

Get out of your way and play.

 

[Johnny StingRay]

To learn fretless, practice in the dark.

 

[Dynomuttasaurus]

Stop thinking. Start playing from the heart.

 

[GeorgesEric]

How can you reach your bass if your thumb is behind your neck?

I play open strings. When fretboard work is needed, I hire a sub. Works like a charm. Paid when paid, no liability.

 

[tiny_bass]

Remember to breathe.
If you can sing it, you can play it. (Ok, 9 words)
Use your ears.

 

[QweziRider]

"You got a great face for radio."

 

[twinjet]

"Relax" [my plucking hand and forearm].

 

[Rib 13]

"If you ever want to do what you want in a band, learn how to sing"

More than 8 words but it is the best advice I ever gotten

 

[fourstr00]

Show up early, relatively sober.

 

[Ggaa]

Keep your fingers in close, both hands.
Bad eq for the room can sound outtatune.
Practice what is hard.
Leave that truss rod alone.

 

[31HZ]

Practice *music*, deliberately, with a goal in mind.

Find a good teacher, and follow their plan.

Making time to practice requires time management planning.

Your choice of bass is of no conseqence.

 

[Ric5]

don't quit your day job

 

[JamesDeGrandis]

What's the best technique advice you've ever been given in 8 words or less?

For me, it was "calm the heck* down"

*not actually "heck"

"Remember, bass is the foundation, not the ornamentation."

 

[silvertone]

This breaks the 8 word limit but heed the words of the master: Victor Wooten
"You Can't Hold No Groove, If You Ain't Got No Pocket."

 

[funkinbottom]

Breath.

 

[ebo]

Buy good gear, blame it when you suck.

 

[tpaul]

"Son, give me the one."

-Bootsy Collins

 

[chris_b]

You always sound like you.