Is there a trick to the 'Find something quests?
Solution 1:
For the Frog quests: Listen carefully. The Frogs croak if you are near them (the louder they are the closer you are)
For The Dogtags: I ran into the middle of the targetcircle and started looking for an encounter. after that the i could find then near the fight in a smaller circle (The tags always had a yellowish shine instead of blue for items)