An Easy Guideline:
1) Choosing between brands = NO NO, because your choosing from your pre-percieved knowledge or influenced by advertisements . If you think Canon / Nikon / Sony / Leica or whatever brand takes better photo, probably you should take a good photo from each of those cameras and ask a PRO to tell you which camera did the photo came from.

2) Choosing between Compact / Semi / DSLR = forget everything your doing now, imagine the size and weight of the camera you wan to bring around.
Hate carrying extra things / want to take good photos in AUTOMATIC mode = COMPACT (Compact can take better "looking" pictures more often than DSLR)
restricted by budget but want something that look better but dont really function better = SEMI
Want to attempt to look professional / be professional = DSLR (Better quality photos but beginners and amateurs will end up with photos worse than COMPACT if you do not have the patiences and interest in photography)

3) Choosing between models of same brand = newer models or more expensive cameras are better