Being Musical Director of Phat Cat Swinger has definitely taught me a great deal about band management from the perspective of maintaining the musical 'book.' Like any decent religion, all good bands start with a good book.
What makes a good book?
Thorough - All the parts are scored together (horns and rhythm section). Transcriptions (i.e. "Take-downs") are accurate. Horn parts are idiomatic to their respective instruments and transposed correctly. Keys are well-chosen. Harmonies are well-conceived, with good voice-leading in the melodies. The instrumentation of the music matches the instrumentation of the band, 100%. The orchestration of the charts strongly showcase the ensemble's brand of sound and diminish any weaknesses. Tempo and style markings are written, loud and clear. Dynamics, slurs, and articulations are written appropriately, removing any ambiguity from the performance. Song structure is easily defined and clear.
Well-copied - Parts have been thoroughly proofread and designed to be read easily by a human being. Collisions of objects have been separated. Notation reflects the direction of the melodic line more than the harmonic accuracy of the piece. Double sharps and double flats are avoided, if possible. Notes and text objects are adequately spaced from one another. Lines consist of 3-5 bars with 4 bars the expected standard. Fonts that aid in the readability and cleanliness of text objects are preferred (Gotham, ITC Avant Garde Gothic, Franklin Gothic, Avenir, Helvetica, etc. are all great). First measures and last measures are indented to help indicate start and finish. Articulations are allowed above and below the staff. Double bars and rehearsal marks are placed appropriately. Page turns and instrument changes (doubles and mutes) are considered with time and space necessary to do them. Lyrics are written with correct separation of syllables. Text directions are brief and concise.
Consistent - Efforts are made to establish a consistency from piece to piece. Scores were designed from a custom template tailored for the ensemble's needs. Fonts are the same, sizes are the same, the 'look' in general is the same. Even the manner of specific preferences of notation stays the same. While this seems to be a 'sterile' way of writing music, it absolutely helps the reader by placing them in a space of familiarity, which reduces performance stress. They'll always know which charts are 'yours' and which aren't on appearance alone.
Protected - Parts are saved in PDF format and stored in no less than 3 digital locations (Computer's Hard Drive, Online Cloud Service, and Emails to Musicians) and no more than 1 analog paper location, if needed. Parts are well organized for easy search and distribution. I personally prefer a location sorted by song and a location sorted by instrument. All locations are password protected. Old versions of parts are saved in "Old Parts" folders nested in the song folders until adequately proven that they aren't and never again will be necessary. All old parts are expunged from instrument folders immediately, however. This avoids version conflicts.
Efficiently Distributed - Parts are served via email with a request to reply confirming receipt. Phat Cat Swinger has been using iPads as a reading device for a few years now. I must say, it makes my job a LOT easier. If your band is using iPads, I strongly recommend using ForScore or PiaScore for reading apps. Avoid using iBooks or storage apps like DropBox and GoogleDrive for the purpose of reading charts, because you can't work with setlists, which slows down your performance looking up each song alphabetically. You can also serve parts in the moment using email, Apple AirDrop and Apple iMessage should someone ever need a chart, even from your phone! Of course, having a paper book might be necessary from time to time, but remember that they can often be difficult/expensive to update or improve.
Why is a good book important?
This sounds like a lot of extra work to a system most would think operates "ok," as is. Indeed, it is a lot of extra work, but as my college Jazz Arranging professor, Jeff Jarvis, would say, "A few minutes at the computer saves a few hours at the rehearsal." If you had the power to rehearse more tunes, more quickly, saving you money on rehearsal hall and personnel costs, would you opt for it?
It also gives you the power to say "Yes" to more gigs, more often, under more challenging circumstances. Players will be able to sub out of gigs. Subs will be better informed about the music and more likely to deliver the show you want. No longer must you forfeit a show because some players are unavailable. When new musicians enter the band, their learning curve is dramatically reduced and can quickly assimilate to your band's "brand." By contrast, players that cause problems or don't put in the work necessary to maintain your band's "brand" can be let go, without fear of losing that player's knowledge of the show and/or the hassle of re-training their replacement.
So, take the time to revisit your books. Look for anything that could be written better, copied better, made more consistent, protected better, or distributed better. Surely, we'll all find opportunities for improvement, but trust that all efforts will be greatly rewarded with better control of the outcome of your shows.