Wind direction - Lift is generated when air flows over the wing. Even when you hold the airplane facing the wind lift will be generated, even before you launch it. This is why you always need to launch into the wind.
There are a several technics to determine wind direction. A few of the easiest ways would be to drop a small amount of soil or a few grass clippings from your hand and watch how they drift with the wind or you could simply wet your finger and hold it up to detect the wind direction. You can also create your own wind sock or simply view your surroundings and watch, for example, how a flag moves with the wind.
A strong wind will have many small turbulences. Usually this is hardly noticed but when you are trying to fly a small and light airplane these properties can make even a 5-10 knots wind a major problem. Try to avoid this by using the early quiet hours of the day when there will usually be little or no wind at all!