mga boss, ask ko lang. new lang ako sa photography. naka buy kasi ako ng flash. pag ginamit ko yung pic ko is sobrang white na parang na flash bang. bakit po kaya. may tamang pag gamit ba ng flash?
please be guided: a friendly reminder
from what I learn from pinoyphotography last 2011
first check your ISO (higher ISO produce lighter picture)
then your shutter speed(the lower the number of shutter speed the bigger the amount of light coming through the lens)
then your lens opening(the smaller the number the bigger the opening)
then check your flash(start with middle power and do the light bounce technique)
"keep on shooting!" 
These should be posted in the Tutorials section but let me expand these:
1. Check your ISO (higher ISO produce lighter picture)
Mas sensitive sa ilaw ang sensor, higher ISO number - less power sa flash.
Also higher ISO means more noise so test what is acceptable to you.
2. Shutter speed (the lower the number of shutter speed the longer the time the shutter is opened, more light will be recorded by the sensor)
Using a slow shutter speed with a flash will result in a blurry background on top of a sharp image that is being taken with a flash. Let's say may friend ka na nakatayo lang sa foreground and sa background may mga sumasayaw, pag slow shutter speed chances are may movement blur sa background ng friend mo. Will depend kung ano ang gusto mong effect, may motion blur ba o sharp all though out.
3. Lens opening(the smaller the number the bigger the opening)
Will also control the amount of ambient light. Let's say I want to use f11 or 16 with a flash, magiging madilim ang background ng subject with regards to flash, pero kung malaki opening, say f4 mas magiging lighter ang background mo. Depends sa gusto mong effect but the most basic is to balance yung flash output sa ambient exposure.
4. then check your flash(start with middle power and do the light bounce technique)
Mas maiintindihan mong gamitin ang flash if your using it in manual mode and start practicing it. Depende rin kasi kung gaano kalayo yung subject mo sa flash. I usually start sa mas lower output pa kesa sa middle. Also be careful kung san mo iba-bounce ang flash mo, kung sa green na pader mo ibobounce magkakaroon din ng green tinge ang subject
Pag shooting ng may flash, let's say party sa gabi - Manual mode, 100 - 125th shutter speed (not higher sa sync speed ng flash), f8 - 11, ISO 400, then adjust flash output na lang. Fast shutter speed para walang blur at f8 - 11 dahil dun pinaka-sharp ang lens ko.
These are experiences of an amateur, corrections from much experienced photographers are very much welcome. I think Randymarsh has also explained this before.
