There's an difficulty option to make it Casual.
For cave, there is a lamp near campfire, you can use it to light up dark areas. Save money and don't rush generator(it'll summon muscas). You'll need an automatic weapon. Shotgun or any semi-automatic weapon is not suitable for this mission. When you think you have enough money to move on, purchase generator and buy an automatic weapon preferably with lots of bullets in one mag. I suggest Bizon(2300$ something) which has 55 bullets. After buying weapon, save for Psycho.
For jungle, I advise shotgun(2300$ one) or the sniper. Sniper can kill 3 goblins with one headshot. Same with shotgun. Then you can buy Psycho. You can quick switch with "Q" to your pistol to disable traps. Don't spam roll too much. You can cheese them and fight near weapon selling machine and headshot them while they're climbing.
For space station, just buy the automatic glock on the wall and go gun blazing.