I decided to post this largely to help newer players. Most of this is well-known to anyone who has played for any amount of time.
1. Pick discs that will be easy to see for where you're throwing. Earth tones in the grass or woods are a bad idea. Bright yellow, orange or hot pink will usually stand out best. Brighter is usually better than darker. Multi-colored discs, like I-Dyed, might seem a good idea, but their broken lines between the colors make them hide like an orange tiger in a green jungle - can't explain it, but they just vanish into the landscape like they're camouflaged. (Don't believe me? Have fun finding your disc, bro.) Also, unless you're into dyeing your discs, don't remove the stamp from the disc with acetone, especially if it's a reflective stamp. Can't tell you how many times I spot the reflection of the stamp before the color of the disc.
2. Write your name and phone number under the disc in indelible ink (Sharpie works fine). None of this just writing your pdga #. Nobody cares what it is, and most people either don't know what it is or won't go to the effort of looking you up. Check your oft-used discs periodically to see if the info needs refreshing as ink will fade with friction and the elements.
3. Watch your disc until it stops. I see this again and again, usually on a bad throw, where the guy turns away and misses a kick off a tree, monster skip, roll, or other unexpected result that places their disc somewhere far from where they will start looking. Your buddies can wait their turn until you're sure your disc has come to a rest.
4. If there's any chance your disc will end up in water, throw one that floats. Period. Don't have one? Get one.
5. If there are OB areas you are forbidden from entering (private property, areas over barbed wire fences, roofs, etc.) just don't throw any disc you want to lose. Throw the one that may not fly perfectly but you could care less if you lost it. Determined to go after it anyway? Congratulations, you're one of the reasons disc golfers have a bad reputation and people don't want the courses around. Go smash a bottle on a tee to celebrate being a dumbass.
6. Either learn what it takes to throw in a moderate to strong wind, or just don't do it. Even if you know the techniques (heavier, more overstable discs thrown on a low hyzer into the wind), you will still get those weird unexpected flights from time to time that travel farther than you ever thought possible - over the road and into the river, most likely. Bye bye disc.
7. Throwing around a corner or into an area where loss is very possible? Unless you're playing alone, have one or more of your buds move to where they can watch and see where it ends up, then do the same for them.
8. Resist the temptation to throw multiple discs. Even people throwing on football fields or soccer pitches sometimes throw their entire bags as practice, then miss one when picking them up because it's easy to miss one in the hoard. Even throwing two discs off the tee on a course makes you more likely to not be able to find one. Just focus on where your lone disc ended up and be glad when you find it. By the time you've thrown your third disc your memory of where the other two went will begin to blur (beer and/or ganja will make this far more likely - Wait dude? I threw others? Seriously?). Also, on the course when people are waiting for you to move on so they can throw, throwing multiple discs is just a dick move.
9. Be rich and don't give a flip about losing discs. Problem solved.
10. If you're going to throw in the snow, use a brightly colored disc (not white, are you brain damaged?). While I've never done it, people swear by taping a 2-3' length of bright plastic wrapping ribbon to the middle underside of the disc. It supposedly doesn't screw with the flight too much and the ribbon might be the only visible sign of where your disc got buried in the white stuff. (Also, for god's sake, do standing throws off the tee - x-step or run up on a slick surface could end your playing forever.) If your disc goes out onto ice over a river or pond - LET...IT...GO.
11. When having trouble finding a disc, try walking toward the sun (assuming it's not directly overhead). It's simple physics - light bounces off objects and hits the back of your eye. By placing the light source on the far side of where your disc is likely to be you increase your chance of seeing it reflecting, and reflection is often the first thing one spots, even before shape or color.
12. I know many won't listen to this advice, but limit how many discs you carry in your bag. Just like it's easier to misplace one when throwing multiples, it's far easier to miss the fact that you left one in a basket, or didn't pick one up that was marking your lie after your amazing putt, if you have a lot of discs. I usually carry, at most, 6 discs, and I can tell in a second if one is missing from my bag.
13. Found somebody's disc? Go to the effort of getting it back in their hands. It's the right thing to do, and you've made him more likely to return your disc if you lose it. Don't return discs? Then you don't deserve to have yours returned. Simple as that.
14. Don't forget to look up. On some courses discs getting caught up in trees is rare enough that we sometimes forget to consider the possibility. Also, just because you've hit the canopy of a tree 200 times and your disc fell out every time, don't assume it did it the 201st time.
15. Don't assume it couldn't have ended up somewhere unexpected. It's easy to misjudge how far or short a disc landed, and there are all sorts of kicks, skips and rolls that can put you far from where you start looking. If you've eliminated the spot you 'knew' it ended up, widen the circle and look where you know it couldn't possibly have ended up - it has to be somewhere.
16. If your buddies don't help you find your disc, get new buddies, and always help them find their lost discs with the same dogged determination you search for your own.
17. Don't assume a disc at rest always lays flat on the ground. It could be on edge in a bush or leaning up against a rock. I once lost a disc that took me over 20 minutes to find - it was on edge wedged between two large rocks.
