Things you will eventually learn (but would have been awfully nice to have known about earlier)

• Don't play your bass right after getting out of the shower. Your skin is wet and the callouses might tear right off your fingers. Give your digits at least 30 minutes to dry out.
• Don't leave basses with active pickups plugged in. Having an instrument cable plugged in to an active electronics system keeps the battery running. When the bass is unplugged, the battery goes inactive. (The same goes for battery powered pedals. Leaving the cables plugged in drains the batteries.) 9-volts are freaking expensive, so you'll learn this one fast.
• Most of the bass tab on the internet is at least a little wrong. But that's okay; think of it as blueprints. For a lot of stuff, all you really need to know are the chord changes. Figure the rest out yourself. It'll make you a better player.
• There's more than one right way to play a song. Sure, there are minor differences in sound between a 'B' on the seventh fret of the E-string and the second fret of the A-string, but when you need to play a 'B,' just pick one and play a 'B.' Don't be afraid to re-arrange tab to make something easier to play.
• If your amp has 'High' and 'Low' inputs, the 'High' input stands for 'High sensitivity'and is meant for the weaker signal from passive basses. 'Low' is for 'Low sensitivity' and is meant for the stronger signal from active basses. (This seems really backwards and counter-intuitive to me, but there you go.)
• Play with other people. You're ready to do this from the first day you get your bass. It's why you picked the bass up in the first place, isn't it?

Slow down and use your metronome

Tick.
Tick.
Tick.
Tick.
1 and...
2 and...
3 and...
4 and...
1 and ah...
2 and ah...
3 and ah...
4 and ah...

Practicing different rhythms to a metronome is probably the most important (and honestly, the least fun) part of my practice schedule. But just playing along to recording, even if it's a simple string of eighth notes isn't the same as practicing along to that click.

By playing to a metronome instead of a recording, you strip away all the other noise and you're left with nothing but the rhythm and your playing. There's no big drums or rhythm guitars to hide when your notes are a little off, or the attack of your plucking or picking is sloppy. You've got nothing else to listen to except your bass.

The other thing that's great about playing with a metronome is how slow you can go. Playing along to a rock song at 110 beats per minute is great, but that speed can hide sloppiness. Crank your metronome down 60 beats per minute and see how your tone is. Are you clearly fretting each note? Are you holding it long enough, and releasing clearly when you're done? How is your right hand doing? Are you alternating your plucking fingers properly? If you slow down and really nail your tone slow, when you speed it up you'll be playing cleaner and sounding better.

I know the temptation is to jump straight from warm-up exercises to playing songs (especially after a long day at work, when bass playing is serving as my wind-down and relaxation time), but in the long run, spending the time and playing it slow will make you a better bass player.