-You can get most of your leveling in through the multiple sidequests in the game; these range from simple collection of items like booze for money/XP to finding missing survivors, etc.
Just note that there's a LOT OF WALKING TO DO in the game before you finally get your hands on a vehicle... this means you're gonna get assfucked by a zombie if you aren't paying attention while exploring for that elusive "energy drink" to keep you alive.
-On the subject of dying, until you figure out what your character's strengths and weaknesses are as far as melee and throwing is concerned, you best not try to go Rambo on the Undead.
One-on-one is fine as long as you can keep zombies at a distance but if you find yourself surrounded or fighting 3 or more early on in the story, run the fuck away because 3-4 hits and you die...
...which in hindsight isn't so bad in the early game because you lose a bit of money and get rezzed to the last checkpoint with all your progress until you died being saved.
-As far as arming yourself to prevent this... BE FUCKING SURE TO REPAIR YOUR SHIT.
There are tool benches you will eventually come across that will allow you to repair, upgrade and even create improvised weapons (Dead Island's Nail Bat > Dead Rising 2's).
As long as you're constantly looting money along the way (investing in lockpicking wouldn't hurt if you're by yourself), you'll always have enough to keep your gear in shape.
-There's also stores involved in the story (starting with Chapter 2, I believe) that allow you to sell the random junk you don't need in the game...
To my knowledge, I have no idea what is and isn't useful with the making of improvised weapons other than 2 sets of nails and a wooden bat and even then I had to earn schematics to get to that point.
-Throwing weapons at zombies doesn't degrade them
-Kicking zombies doesn't cost stamina
-While you can upgrade your stamina and stamina costs so you can wail on the Undead longer, you will tire and that's when they get you.
Pick your battles, kick those zombie fucks onto the floor and aim for the head.
