You should give an example of where, conditions, and for how long, and what kind of “wildlife” will you encounter. SWPL pretty much sums it up, but I’ll blow hard.
I believe statistically the number one danger is dehydration. Carry more water than you think you’ll need. (All the other no-brainers as well: dress in layers (if possibility of cold), let someone know your trip and when you’ll be back, know where you are going or have someone with you who does (e.g. map, compass, geo, etc.) Don’t be afraid to backtrack if you get lost. Don’t force it.
I think “snake-proofing” is more about paying attention. Summer is snake season, so we’re in it. Don’t be the “cell phone freeway driver” when on the trail. Watch and listen carefully and confidently as you walk. Snakes don’t want any part of you (or mountain lions or bears for that matter). If you’re going into a risky area, make a big noise to let them know you are arriving, and they will clear out. Snakes can only uncoil to just over half of their length, so the actual danger area around you is pretty small – well within your sight. Use ankle boots if you have them. I don’t think snake-proof gaiters are needed, but they exist.
If you square up on a mountain lion (probably only early morning or dusk – especially dusk – when they generally feed), and if they do not instantly run away – DO NOT RUN. Square up and make yourself as large as you can (e.g. lift a mountain bike or hands above your head) and make as much noise as you can. Running or turning away will make them instinctively want to taste you. If you are attacked (90% chance you won’t know until after the fact), protect your throat and do not ever – EVER – give up. Grab a rock, or a stick, or poke them in they eye, or grab a leg and break it … you get the idea. Mountain lions are not bears. Playing dead is the last thing you ever want to do. If you’re way in the outback, best thing is to be next to a man with a gun.
Everything else is small stuff. Literally.
Mosquito-proof is more about time of day (dawn and dusk). Some people like to feel good about themselves with eucalyptus based repellents. Me – I like hard core purpose-built industrial strength insecticide. The higher DEET value the better. When I know I’ll have to walk a trail at dusk, I put on repellent over my whole body, but also carry a net to cover my face. Critical that. Get the spray because you’ll need to cover your clothes as well. They will bite right through Levis.
“Parasites” should not be ingested. Never drink trail water. Giardia is a VERY ugly critter. If you can’t cary your fresh water, purchase a proper camping portable water filter. Talk to a professional for the right one.
The tick/flea type parasites you can buy repellent for as well. Ticks should be pulled out slowly, from as close to the skin as possible. You should pull enough so the skin pulls up, but you may need a min or two for him to decide to let go. Do not yank him out or the head might come off. If the head does come off, and remains in the skin, you have to dig it out.
Poison oak/ivy can be a real problem. Of all the things mentioned so far (I have encountered them all) I am most afraid of poison oak. I’ve had golf ball sized blisters. I literally have scars on my shins. Oh the tales of woe.
You must know how to identify it. Leaves of three, run and flee was the Boy Scout mantra.
Hope some of that helps.
Oh – the most important part: Port wine goes down best by a campfire. Get a little 10oz Nalgene screw top and dedicate it to camping Port wine. It is a mysterious and magical drink by a campfire. Nothing goes with campfire like Port.