Press ~ to open the console window, then enter any of the following codes, then Hit Return.

please god God mode

please giveall All items

please killall Kill all enemies

please open Open all doors

please fly Flight mode

please ghost No clip mode (This one is Amusing, you get to view the entire level)

please invisible Invisibility

please tellall All Info

please refresh Full Health

Agent
Know your weapons well. Each weapon has a different handling and ballistic characteristics, so you should get aquainted with each. Somr weapons are better for different missions than others.
Never run when you are trying to get close to a Dinosaur. They can hear and see the movement. Walking makes more noise and attracts dinosaurs from greater distances.
In a close quarters battle, dinosaurs have the upper hand. Thinning the herd before you get close to it will give you a better chance for survival.

Dinosaur
Try not to attract too many agents at once. It's best to take on one Agent at a time.
Be sure to feed (E key) on dead agents and dinosaurs to restore your health.
Agents can cause a lot of damage from a long range. your best chance for taking down an agent is to not let him see you untill you're within attack range.