I would do some research regarding a fitness plan that is specific to you. There are plenty of workouts that help enhance the muscles used to complete the Marine PFT. That being said, nothing improves your score better than doing pull ups, crunches, and running.
Pull ups: Just do pull ups. Train your back and shoulders if your an overhand gripper. Train your biceps if you prefer chin ups. If you have access to a gym, take advantage of that opportunity.
I always do a 2 minute set of crunches before running. You can also do leg raises and planks to strengthen your abs.
As for running, what helped me was mixing in sprints after I built up my endurance. I suggest running daily; certain days with difficult runs and others more mild. Another quick way to build up endurance is swimming, but if you “over-swim,” you will fall short on dry land training. If you choose to stick with dry land, train your legs at the gym as well.
Best of luck!