When transcribing orchestral works, the arranger must replace string tremolos with horn/cornet repeated notes or vibrato. Woodwind passagework is best assigned to cornets (for agility) or tenor horns (for a more rounded articulation). Sustained orchestral chords can be distributed to the whole band, but care is taken to avoid "brassiness" by marking dynamics lower than the original.
I hope this helps! Let me know if you have any questions or need further clarification.
Happy arranging. May your chords be resonant and your rests be counted.
Brass band scoring should exploit idiomatic effects: stopped (hand-muted) cornets for a nasal, distant sound; cup mutes for a smooth, veiled quality; and straight mutes for brilliance. Open "rip" glissandi are possible on trombones but not on valved instruments. Valve tremolos (rapid alternation between two notes) are effective but limited to intervals of a second or third. Multiple tonguing (double and triple) is standard on all instruments, but composers should indicate phrasing clearly.