This is where you want to be careful. If you tighten the strings way too much they may snap. For tuning notes, refer to the Online Bass Tuner. If you don’t know how to tune, check out the page on how to tune a bass guitar. If you've never done this before, you may want to use an electronic tuner to be on the safe side.
Bass Guitar Tuning Notes
Tune each string to its appropriate pitch.
From lowest pitch to highest, a 4-string bass is tuned E A D G.
5-string basses are usually tuned B E A D G.
After you string your bass, it may take a day or more for your new strings to stretch out, but you can help them along.
Once you are tuned to pitch, hold each string around the 12th fret and gently pull on it to stretch it out some. Then tune it up again. Usually it doesn’t need to be done more than twice on each string.
If you’ve followed everything in this how to string a bass tutorial, your bass strings should be on correctly and will stay in tune pretty well. Hopefully you've avoided causing any major injuries to you or your loved ones throughout the bass string changing process.
A couple other bass string tips:
Always tune up to the right pitch. This way the bass tuner is less likely to loosen on its own and go out of tune.
To add life to your strings try wiping them down after each time you play. You can also clean your bass strings periodically.