There are a few items of clothing and fishing gear that will make your fly-fishing experience a bit more comfortable, pleasant and safe.
Fly boxes are one of those essential items, ideally at least one for dry flies and one for nymphs and wet flies. Also use separate boxes for your saltwater flies and categorise your flies.
You will need a landing net with a reasonable length of handle. Some nets have a clip on them which can be used to clip them on to your a belt or even onto the back of your fly-vest or waist coat. You may need a bigger landing net for saltwater use. You can also get a net with an extendable handle that makes it a bit easier to reach a fish when it’s difficult or not possible to bring the fish close in.
A pair of polarised sunglasses is another essential item. Wearing sunglasses will protect your eyes from when casting, particularly on windy days, and makes spotting fish in the water that much easier.
A pair of small scissors or a fisherman's clipper is needed to trim the loose ends on knots, either when attaching a length of tippet to your leader or when tying a fly to your tippet. Scissors or line clippers can be attached to the front of a waistcoat with a zinger which is a small spring loaded device that pins to tour waistcoat.
A backpack can be useful for carrying your lunch, water, warm clothes or any other essential items that you can’t fit in on onto your waistcoat. It will however tire your shoulders, so don’t pack too much in there. Instead of a backpack you could also use a hydration pack that has a few pockets to store the items you would put in your backpack. Quick dry trouser is also useful when you fishing the rivers or streams. The last thing you want is an uncomfortable wet trouser.