A few recommendations on what to pick for the starting loadout
-3 Fuel
-1 Ammo
The Goal of this loadout is to never run outta gas the reason being is that it's 24 fuel.
Another reason why I'm suggesting this loadout is because you have 200 ammo at the start of the game, this should give you plenty of time to get food and trade for any tires/batteries/mufflers

Or
-2 Fuel
-1 Ammo
-1 Muffler
The Goal of this loadout is instead of hoping that you won't break down when trying to get to your first stop, you have something to provide extra protection.

If you think that their are better options that you should pick
Well here are thing that you shouldn't put for your points
-Money or Food
The reason being is that for 50 money you can buy
about 100 ammo compared to picking the 200 ammo at start
a muffler with 20 cash left over(verses picking 2 mufflers instead)
a medkit late game for 40
or 8$ for 10 food

The reason you don't pick food at the beginning of the game is that you can just scavenge it
And 8 fuel is worth more than 250 Food

When Scavenging the best method is to line up the zombies in a nice little train, in other words avoid them
-When the Zombie Activity is Low (10AM-2PM )
It's safe to go out try not shooting it's save to grind and stock up (Max 3 Ammo needed)

-When the Zombie Activity is Medium ( 7AM-9AM/3PM-5PM )
It's still ok to be out during this time, only if your low on supplies/ Not recommended to go out if your party leader is low on health (Up to 5 Ammo Needed)

-When the Zombie Activity is High ( 3AM- 6AM/ 6PM- 9PM )
You should only go out during this time if your outta food. If you have at least 75 food just put rationing to small and wait out until Medium or low Zombie activity. If your party member is low on health use extra ammo (between 5-15 ammo needed)

-When the Zombie Activity is Deadly ( 10PM-2AM )
Same thing with high activity. But here's a tip when waiting through until Medium activity
-Trade
-Sleep/Fish with low or high rationing
If your outta luck and on your last leg and you can't wait an hour make the call and go (max 17 ammo)

When trading keep these values in mind

Medkits/Tires/Batteries/Mufflers worth is around 30 money
Fuel is worth about 25 money each
Ammo is worth 24$ for a 20 pack
Scrap is worth 5$ each
Food is practically worthless If someone asks you for food it's a deal
Money is money, if you find something cheaper than this value it's a bargain

It's good to have this amount at all times

-Party members and Car above 50% Health
-Fuel at 4 or more at all times (bandits steal)
-At least 50 Ammo
-16 Scrap
-1 muffler, Battery, and Tire
-And at least 150 food at all times

Reason behind this

Lets say that your on your way driving to the old gas station on the DLC
If your not meeting one of these requirements
One of these outcomes could occur

-Won't be able to shoot
Which negates the use of scavenging
or the protection that you need for roadside events
-You won't be to feed your party, Lowers health
-Your car won't be maintained properly, Constant breakdowns
-And you will need to scavenge constantly/Trade 24/7 for fuel and other supplies

The methods that I know of are
Drag And Drop
Best use case is when your out in the open and distant from zombies
let go here Drag from here
(You) (Zombie)

Flicking

Flicking is where you take your mouse and flick it from 8 directions to attack the zombie quickly, can be done while running. This is more risky because your not going to always hit with this method.

When to take the rifle
-When you have fast bullets
-When you are trying to conserve ammo
-When you want a Daily use weapon

When to take the Shotgun
-When you like wasting ammo
-When you have fast reload
-When you have 200+ Ammo

When do you take out the Pistol
-When you think that you have to take a crowd of 4 in a short time
-When you have fast reload

Medkits are recommended for healing the Party leader
Other party members can heal on their own with the use of food
If a Party member is Incapped that is the time to use it
also If you have one left and your party leader has some damage taken, I recommend that you use it because bandits love stealing Medkits.

I recommend that if your considering an upgrade
that you get at least one of these
-A upgrade for an unbreakable muffler/battery/tire
-toolkit
-Solar panel