Hi Guys, thank you very much for the valuable advice!
I tried using M mode so to learn better photography. It's not easy but I think such grilling is essential for me to become a better photographer. But I always have a problem with under/over exposure and I resort to cranking up/down the aperture/shutter/iso speed. So I ended up taking too long to take a good shot. The subject might not stay there long enough for me to get it right! To sum up, I have no problem with composition but I am struggling with getting the correct exposure.
I think it's probably better to use Av mode as some of you have suggested?
With digital photography it is more convenient as auto focusing is taken care for you subject to the effectiveness depending on lighting situations.All you need to do is point and shoot if you were on P mode.I think you need to understand the basics of exposure because
it is reciprocal in nature between aperture and shutter speed in relation to ISO sensitivity.When you do it becomes automatic and your thought process can be integrated to your composition.Then just click and you've got the picture ,almost intuitive.
Exposure is another matter as you need to know how your camera's metering system is designed.Most metering is of the averaging
type,meaning if you read the marketing blurp like matrix metering where the sensor is divided into a tic tac toe pattern but with more
squares or sections and each square's light reading is all added up and averaged over the entire grid which then becomes the aperture or shutter speed in relation to ISO speed/sensitivy.Of course you have spot metering where a certain area of the scene mostly center
as you tend to put important subject and the eye normally concentrates to get a more accurate reading rather than average to emphasize the tone/texure or highlights.In essence you would select an exposure between average and spot.Lastly there is centerweighted metering where a larger area is selected.This in turn is related to white balance/colour as average metering is calibrated to give a neutral grey for film technology but for digital it is the white tone or shade which determine the colour or shade of colour of different light sources like daylight and artificial lighting.Learn about the nature,properties and colour of light,it's interesting.
In photography "half the battle is won" if you get the most accurate exposure as that will mean optimum colour and contrast.
The rest is art or creativity or sometimes plain trial and error ( bracketing your shots) or luck ( time of day or circumstance).So you need to do your homework to be a better photographer.
Sorry for causing so much frustrations here. As a newbie, we sometimes don't know what we don't know. But I get what you all are saying and the advice is great! Thanks!
That's your perception don't take it personally although some could have put it across in a more pedagogical manner.