Visual Flight Rules (VFR) - set of regulations under which a pilot operates an aircraft in weather conditions generally clear enough to allow the pilot to see where the aircraft is going. Specifically, the weather must be better than basic VFR weather minimal, i.e. in visual meteorological conditions (VMC), as specified in the rules of the relevant aviation authority. The pilot must be able to operate the aircraft with visual reference to the ground, and by visually avoiding obstructions and other aircraft.

IFR
FAA’s Instrument Flying Handbook defines IFR as: "Rules and regulations established by the FAA to govern flight under conditions in which flight by outside visual reference is not safe. IFR flight depends upon flying by reference to instruments in the flight deck, and navigation is accomplished by reference to electronic signals
Flying at night requires an understanding of how darkness affects a pilot’s vision and what you can do to make sure you make the most of your night-limited vision.

The most important aspect of night flying with respect to vision acuity is to realize that it takes 30 to 45 minutes for your eyes to fully adapt to minimal light conditions. And if you look directly at a bright light for more than about a second, you’ll need to start the clock all over again and reacclimatize to the darkness.

That’s why it’s important to turn down cockpit lighting at night and avoid looking directly at bright lights. This process should start on the ramp before you ever climb into the cockpit, giving your eyes time to adjust before takeoff. Once in the air, if you need a flashlight, use one that allows you to turn down the gain so you don’t overdo the brightness and start back at square one.

It’s also important to understand that it can take longer to find certain controls in a dark cockpit and plan for that fact. If you’re a renter and fly a number of different airplanes, you’ll want to be certain you are completely familiar with the cockpit of any aircraft you will fly at night.

One way to accomplish this is to perform a blind cockpit check. To do this, sit behind the controls of the airplane during the day, close your eyes and try to locate the throttle, mixture and prop controls; light switches; landing gear, carb heat and flap levers; radios and GPS navigators; critical circuit breakers; altimeter and heading indicator knobs, and anything else you’ll need to manipulate in flight.

Subtle differences even among the same type of airplane can add to the time it takes to find a particular knob or dial. If you can locate them all bind-folded, you’ll be much better prepared when flying at night. Source

Flying VFR Like IFR
Identify the Risks
The key to making VFR flight safer is to fly like the airlines do. Of course, that’s not always possible. A Bonanza pilot flying a 500 nm trip to an unfamiliar small airport doesn’t have the second pilot, the second (turbofan) engine, the dispatchers watching his back or the same level of required recurrent training as airline pilots have. While flights of small airplanes come to harm for many reasons, the biggest risk factors can be summed up in three main categories: weather, terrain and loss of control. If we were to remove these offenders from the record, light airplane accidents likely would be cut by far more than half.

Use the Tools of IFR
The key to far safer VFR flight is to fly predictably and to avoid the big areas of risk. That means borrowing everything you can from the IFR playbook to keep from hitting the ground unexpectedly, which never ends well.

Fly the Airways
A great approach on this flight if you’re VFR-only is to ditch the “direct to” button on the navigator and fly airways. I can’t stress enough how much just this tactic can help. For one, most airways will follow the lowest terrain along your route of flight (that’s why they were invented, remember), so you don’t have to figure out your terrain clearance. The airways have done it for you. In good weather this helps you figure out your desired altitudes ahead of time, so you know if there’s a healthy climb required ahead. When the weather’s bad, it gives you an out.

Stock Your Tool Bag
Being too low en route seldom (not never) causes accidents in clear weather. It’s when the weather gets dicey that things get hairy. The two biggest tools to have at your disposal are, one, being able to keep your airplane under control if you somehow lose visual reference and, two, having a way of knowing where the terrain is to avoid hitting it if you were to go IMC. If you’re flying the airways when this happens, unless there’s severe ice or convection, there’s no emergency involved. You just keep flying the airplane by reference to the instruments. Remember, the single biggest risk with inadvertent VFR into IMC is losing control of the airplane. Source