Personal Requests And Notice Board
The Notice Board in the Gryffondor common room usually gives a location, but higher up as you near completion they start to give vague clues, such as "Could be anywhere on grounds". With personal requests, they do not ever really give you a clue, except the first one. However, the items are near the area in about a two acre search range.

Finding Lost Items
When in doubt, check Hagrid's Hut. Many of the lost items end up there.

Fighting With Expelliarmus
When in one of the few battles with Hogwart's students (just the Slytherin Gang, all others leave you alone), let them make the first shot and bounce it back. Just as you do, use your Flapendo with a quarter to half second charge to knock them back, thus trapping them with two spells to knock back, which they can never manage. Note: Beware, just as you finish casting Flapendo (depending on distance), you will be forced to use your Expelliarmus almost instantly.

Expelliarmus Challenge
Use your spell that cuts down tapestries and ropes on the spiked ball. Walk up close to the edge and hold your trigger button (default R1), charge up for a half second and cast. Note: If you throw the imps into the fiery pits, they will die and you do not have to worry about them. Likewise, if you throw them all away you cannot put them into the cages to get out; but when all are indeed gone, they respawn from that hatch in the wall at the first ramp.

Easy Points
In the Chamber Of Secrets, destroy paintings on the wall. You will open the painting and get 100 points for Gryffindor. After returning from the Whomping Willow, head deep to your right when Professor Snape finishes scolding you. There, in a corner, you will find your first Notice Board Item. You can return it to the Notice Board before or after you go to the Restroom Shop the Weasley's set up, earning you the very first 10 points in the game, and possibly a Wizards Card.

Free Sickles In Diagon Alley
Once you have collected your Standard Book of Spells (Grade 2) in Diagon Alley, cast Flippendo to break barrels and find Sickles to buy other things in the shops. There are 3 places where you can do this, and return 3 to 4 times after going into a shop.

Get Nimbus 2000 Broomstick
On the second day of school go to Quidditch practice. Get a "B" or better to get Nimbus 2000. Now you can fly around anytime during the day, exept in the school. You can only land on grass.