How to write instrument names in a standard professional way in the sheet music

Question

This question is about how to write instruments names on a score.

On the page at:
https://musiciandevelopment.com/2016/05/16/how-to-prepare-a-professional-score/
it states:

list the full instrument names and include all instruments. In subsequent systems, use abbreviations for the instrument names (if you only have 1-2 instruments, you can omit instrument names entirely).

I have 2 human voices in my song and a piano (expressed by 2 staves exactly); each of the human voices have exactly one stave. So there are three instruments in total (which are 2 human voices and a piano).

Following the above quote, when the instrument first appear in the music I am labeling it as "Voice 1" as the main voice, "Voice 2" as the background voice, and the other 2 staves as "Piano" where the 2 piano staves are indicated by a curly right bracket (see image).

On following lines, at the beginning of each such line I use the abbreviation "V1", "V2", and "Pno." for "Voice 1", "Voice 2" and "Piano" respectively.

I have sketched out a representative sheet music in the image to describe the above notation:

My question is: Am I writing the instruments in a standard professional way in my sheet music?

I expect this is an easy question for someone with more experience than me—but notating music is a learning process for me.

Update: after reading the answer I think that the following, sketched below, would be a good way to do the notation. Showing Voice1 (main voice), Voice2 (backing voice), Piano at the start if the first line of bars. The simply using the square bracket for the two voice staves and the curly bracket for the two piano staves for the remainder of the sheet music and where each line of new bars start. I think using this notation it is clear what is meant-it is for a pop song,on a single piano,with backing vocal where the backing vocals has different words to the main vocals-though I think the same notation would apply for the hypothetical scenario of if the words of the two voices was the same words.

Answer 1

Different editors and publishers will have different guidelines (like with style guides for newspapers or scholarly publications, there's plenty of variety in music publishing as well), so there's no single "correct" way to do this.

Now, from my personal experience as a classical musician, in the case of vocal music with minimal accompaniment (only piano) like this, it is unnecessary to repeat the instrumentation at the start of each system, as it will already be obvious (due to the braces) which staves apply to the piano and which ones (due to the underlay of lyrics and the order in which they appear) apply to which voices. This can be seen, for example, in this piece from Schumann's Op. 114 (ed. Breitkopf & Härtel):

It might also be possible to entirely omit indications, though that is more usually seen with Lieder for a single singer than pieces for more voices, ex. Schubert op. 3 no. 3 (ed. Peters):

One thing I would note is that if you have specific vocal ranges (soprano, mezzo-soprano, ...) in mind, it would be better to indicate those than merely "Voice 1" or "Voice 2". For example, from a cantata by Bach (BWV 110, Neue Bach Ausgabe, ed. Bärenreiter):

Finally, little addition not strictly related to your given example, the recommendation to write the instruments at the start of each system might be more of a practical concern in orchestral scores (where there may be a much larger number of instruments in the score), though even that is far from universal, as a look at editions of Beethoven's 9th Symphony (link) - an example among so many others - will reveal. In any case, as the score in such a case is intended for conductors and not individual players, this rarely poses problems as (professionals, at least, your mileage may otherwise vary) conductors will tend to know the pieces they're conducting very well and will also be used to the standardised instrument order one sees on such scores.

Answer 2

AlexJ’s answer gives some excellent specifics; but another important general piece of advice for all questions like this is: look at good-quality published examples of pieces/songs in the same genre.

This makes sure that you’re finding the conventions appropriate to the genre — jazz, classical, pop, and other sheet music traditions all have slightly different standard choices. It also gives you the best footing to judge what you like — when you read/play/sing from the printed piece, which was easier to use? Was it too sparse or abbreviated and difficult to understand, or was it too detailed, with unnecessarily repeated markings getting in the way?

If notation guides/textbooks (and advice like AlexJ’s) and published examples all agree on some point, then almost certainly, that’s good practice to follow. If they conflict, there can be many possible reasons. Maybe the guide is describing conventions from a different genre (classical vs pop, art-songs vs folk-songs, …) Often guides and advice can be more conservative — describing the standards of a generation ago, when publishing practice has moved on. Conversely, sometimes publishers can be sloppy or cheap, and use notations that are quicker to write/typeset but harder to read (especially common in American mid-20th-century publishing, in my experience) — guides are more likely to describe “best practices”. So by combining guides with a range of examples, you can consider all these and make an informed choice which models to follow.

Finally, looking at similar published pieces is good to do anyway anyway for many reasons — it will teach you more about all the conventions and techniques of the genre, both notational and compositional.