Here is a list of things I check every so often so that the only thing I have to worry about is the trout.
1. Clean or replace fly lines.
My fly lines suffer the most because of use and abuse. A fly line on a client rod may only last me 4-6 weeks during the season. The average angler will probably get a few years out of their fly lines when taken care of. When they are just a bit dirty I use a felt pad and cleaner specific for fly lines. My favorite is a product called Glide, but they all seem to work well. You also only need to clean the first 40-50 feet of your fly line. That’s the section that gets the most use and always the dirtiest. You can also wash them in two buckets of soapy water but I have always felt that dealing with all that line is a major pain.
2. Check the date of leaders and tippets.
I always put the year I buy on my leaders and tippet spools. If they are more than a year old, I toss them in the trash. Monofilament and Fluorocarbon hate sun and degrade pretty fast. There is nothing worse than trying to tie on a fly and the knot keeps breaking over and over. Keep your leaders and tippet spools fresh and you won't have problems when out on the water.
3. Check waders for leaks.
Nothing is worse than sliding into the river on a warm spring day to find that you have a leak in your waders. A quick visual inspection works well, but I will also fill my waders with water in the shower to just off the knee level (otherwise they get very heavy) and see if there are any problems. If so gore-tex waders are easy to repair. See the blog for the how to repair waders.
4. Organize flies.
I have too many flies. But that’s all right. It’s an addiction that many fly anglers suffer from. I like to go through my boxes and throw out any rusty hooks and flies with rubber legs that may have become brittle or stripped off.
5. Clean and oil reels.
For the salt water fishermen you're used to taking special care of your reels. For us trout fishermen, reels require a lot less attention. But once a year I like to take the spool out and use a q-tip to clean out any dirt and grime I find. I then will use a reel oil (used sparingly) and add a few drops on the spindle and other working parts to insure to keep it working smoothly.
6. Check inventory of supplies such as floatant, dry shake, split shot, indicators, etc.
Nothing is worse than being on the river and reaching for my dry shake to see that the bottle is empty. I go through my fly pack and make sure that I am fully stocked on the essentials.