I don't think anyone mentioned know your fretboard, i.e. know where the notes are.
Tabs are OK to peek at, but, are a dead end if you have to rely upon them for everything you do. So I am going to point you to fake chord and or lead sheet music. Here you are given the chord name and the lyrics. If you sing the lyrics (under your breath is OK) you know what chord is coming up and you get a feel for the tempo of the song - two good things.
Just in case you do not already have these two charts"
Link Removed
The Major scale box pattern
The box, how to use it. Those numbers are the fingers you are to use in fretting the strings - to get the notes - 1 = index, 2 = middle, etc. Pattern takes place over four frets and you have four fingers. Yes, helps if you use the correct finger. Notice the red circle, that is your root note in the pattern. You place that red circle over the chord's name on your fretboard, i.e. want to play the C chord, find a C on the 3rd or 4th string and place that circle there, i.e. the 3rd string 3rd fret or the 4th string 8th fret.
Here is how to use those two charts
http://www.talkbass.com/forum/showthread.php?p=9372867#post9372867
Google can call up some fake chord or lead sheet music for you. Use these key words:
Chords, "name of the song" --- or Fake Chord, "name of the song". The comma and quote marks do help.
Fake chord:
(C) Happy birthday to (G) you,
happy birthday to (C) you,
happy birthday dear (F) ----------
happy (C) birthday (G) to (C) you.
Right at first just use roots later on you can add the other chord tones found in the chord, but, for right now roots will play a lot of bass. Sing the song under your breath and sound the C note (3rd string 3rd fret) one sound for every lyric word - yes hap-py takes two notes as will birth-day. When you get to the word "you" change over to the G note (4th string right below your C) and do the same until you get to the "you" again and this time change back to the C note. OK where is that F note you will be needing? Right above the C. Isn't that convenient. That was not an accident if you place your root on the 3rd string a I IV V chord progression will always be like that. It's going to be fun.
Check out the following I IV V chord progressions:
Key of C = C-F-G
Key of G = G-C-D
Key of A = A-D-E
Key of D = D-G-A
See how all of those line up on your fretboard. Piece of cake.
Play from fake chord or lead sheet and roots alone right now will let you get a feel for your instrument.
www.studybass.com is a friend.
Here is what you will be doing couple months from now.
http://www.studybass.com/lessons/common-bass-patterns/roots-and-fifths/exercises/ Exercise 1. Ever basic chord will have a root, a five and an eight. So that pattern is generic and the same pattern can be used over all the chords in that song. Yes, even a minor chord. Why? There is no 3 in that pattern it's like a generic power chord. Hint - get that pattern into muscle memory.
Three months from now.
http://www.studybass.com/lessons/common-bass-patterns/root-fifth-flat-seventh/exercises/ Time to move beyond generic patterns and pick up some non generic notes in your bass line.
Have fun.