I think it sooner or later happened to all the bassists of the world: you’re playing a song, from the line of bass quite repetitive (and consequently boring), and at some point you want to insert that “thing” that on the record it’s probably not, but if it comes out you think it will be appreciated, and in any case, you’ll have a little more fun.
It happened to you, right?
The problem is that often you do not know what to do, or everything that comes to mind you do not like; often the problem is that the space is really limited ( less than a bar ), maybe the tempo of the song is quite fast, and the consequence is that we do not do anything, or if we do it, then the result does not satisfy us.
How to do?
Today I try to give you the rules, 3 simple rules to keep in mind and from which you can start to develop your ideas, your “fill”.
With the term “fill” usually refers to something that has more to do with the drums than with the bass, but we borrow the term to identify what we actually do: a “break” within the usually groove, which connects us to the beginning of a new song sequence (a new verse, the chorus, etc.).
The main difference compared to what the drummers do is that we must also think about the notes, and it is from here that I want to start: first of all establish what you want to draw: the key of the song? The notes of the chord on which you are at that moment? The blues scale? You can use what you want (which is consistent with the song, of course), but it would be a good idea to think about these things before throwing yourself into a phrasing (especially if you are a beginner or otherwise this situation is an obstacle for you).
Deciding what to use also leads you to decide accordingly to the area of the keyboard where you want to operate; it is often more useful not to move too much from the area where you are in accompaniment, especially if the song is fast; in principle you can adapt your idea to the part of the keyboard where you are.
To succeed in a good phrasing, however, the second rule is even more important: rhythm. A beautiful phrase is a phrase that is also interesting from a rhythmic point of view. Try to think how a drummer would do: for them the rhythmic component is very important, not having notes. Imagine a drums fill at the point where you would like to insert your bass fill and then try to put notes on it, following the criteria with which you have thought them following the first of these 3 rules.
The last but most important rule is this: do not overdo it. The fill is nice if you put one or at most 2 times in a song, not more. Do not look for finesse at the end of every single part of the song. First of all you would risk colliding with the drummer’s real fill, making sure that you do not understand what you are doing or what he is doing.
In addition, too many bass fills are losing attention and risked in this way that they are not appreciated.
So, my advice is: practice at home, playing on records, and in that situation elaborate as many ideas as possible. When you play with your band, choose strategic points ( according to your drummer) and also choose your best fills, previously studied. There will always be time, in the future, to improvise them.
Are you ready? Embrace your bass and start having fun!