Generic post first:
List of lists:
http://www.gamesas.com/index.php?showtopic=1010109
Top 100
http://www.tesnexus.com/downloads/top/alltime.php
Files of the months:
http://www.tesnexus.com/downloads/filesofthemonth.php
Hall of fame:
http://planetelderscrolls.gamespy.com/View.php?view=oblivionmods.HOF
List of topics exactly like yours that have already been answered: (You can also find my favorites in post #4)
http://www.gamesas.com/index.php?/topic/1072579-the-any-mods-list-of-topics/
If you want any further help I suggest you tell us about yourself; what you like and what you're looking for... Here's some questions to get you started:
Have you played Oblivion already?
What sort of things interest you?
What type of Character do you usually play? (good/evil, theif/mage, roleplayer/random-no-story-hack-and-slasher?)
Are there specific types of mods you think would interest you? (Quests, graphic mods, gameplay mods, overhauls, etc.)
When did you leave?
What things bothered you in unmodded Oblivion?
Since you're new to modding I wouldn't recommended going overboard. Just get a few small mods and slowly add to it. Just make sure you don't get any buggy or massively conflicting mods, because later on when you start adding more complex mods that can kind of screw you over.
A mod that adds a chest with a sword in it? Those type of things will usually cause no problems. Deadly Reflex/Unnecessary violence, or poorly made dirty mods? Those should be pretty scary for you (well dirty poorly made mods are scary for everyone.)
Some recommendations of mods kind of like what I described:
http://www.tesnexus.com/downloads/file.php?id=25844
http://www.tesnexus.com/downloads/file.php?id=26196
http://www.tesnexus.com/downloads/file.php?id=3409
http://www.tesnexus.com/downloads/file.php?id=21862(good for troubleshooting)
http://www.tesnexus.com/downloads/file.php?id=20736
http://www.tesnexus.com/downloads/file.php?id=25462 (might have some compatibility issues with other guard mods like RGO, but nothing too serious)
http://www.tesnexus.com/downloads/file.php?id=21989 (Quest mod that only adds one NPC and one cave to the world, but the cave leads to a huge new world space.... In my experience, unless it's poorly made or uses complex scripting quest mods are usually pretty safe.)