Always cut only on the right side of specimens. Do not overstuff jars. It's best to let specimens fix with plenty of space around them so they are fully extended and fins are fixed in expanded position. Often this is best done in 5 gallon buckets, not in jars. Sealed jars laid on their side also allow smaller specimens to extend and not end up curved to match the inner jar walls.
Distorted specimens are difficult to measure and examine.
Label your specimens immediately with complete information on quality tags. Pull tissues and freeze or dry fin clips, scales, etc. Develop a system and keep careful notes in your field notes. Bulbs and fluorescent fixtures can be filtered, but lights should always be off unless workers are in the collection. Compactors can be used to reduce space required by shelving.