This may sound silly and remedial... but:
1.) MEMORIZE the musical alphabet forwards, but more importantly backwards, until it is second nature to you.
2.) MEMORIZE the bass Clef. Dedicate the Lines to memory... until you don't have to think twice what the lines and the spaces are on the staff.
3.) MEMORIZE the First 5 Frets and Open Note on Each String.
The later two can be achieved by making excercises for yourself, work one string at a time...
Write out the the Notes on a blank Staff(Start with one String)Write out all the notes for that string in random patterns, and play along with the notes as you sight read them. Then work your way through all the strings.
Sight reading Music, is much like learning to read the English Language, you practice and practice, and then certain phrases and terms are committed to memory before you know it... When you first started reading at school, you had to sound everything out...but before long you don't even have to think about how the sounds work together, you simply memorize whole words.
Here are some resources that can help as well...
http://www.studybass.com/tools/bass-clef-notes/ http://www.musictheory.net/trainers/html/id81_en.htmlHope this helps.