Easiest will be from doing repeatable exp quest.
Each quest will give u 10 or 20 fame depending on your level.
The NPC is located near to Santa in Barantan since you're Yllse.
He's a knight in full armor just above Santa.
You can refer more details on the exp repeatable quest here - viewtopic.php?f=11&t=25134
Check on the Monster Hunt - Leveling Quest
Alternatively, you may refer below for one time fame quests.
Check here - viewtopic.php?f=11&t=633
I can also share the best way to farm fame as new character.
I did this myself and casually get from 1k to 7k fame in 1 week.
If you do non-stop, 7k fame is doable in 3 days or so.
Make new character and level to 91.
Make sure you don't level more than 99 or this can no longer be efficient.
At level 91-99, the Monster Hunt exp quest will require you to kill 50 normal Ettins. At 100 it will be 25 Dark Bears which will not be efficient.
You will gain exp and 10 fame per Ettin quest.
Pro tips: you should always put party exp to spell or weapon to avoid the quest exp you get from getting your level to more than 99. Alternatively you can buy Exp Nullify potion from Santa for 500 RE.
Do this quest repeatedly until you get however many fame you need.
The reason why Ettin is most efficient because, at lower levels than 90, you will get random monsters to kill.
This will cause a lot of travel time loss.
At 91-99, it will always be Ettin.
For Yllse it's quite a long walk to their pit in Light Dungeon (2 mins or so).
Since quest and spawn location is fixed, the whole process is macroable.
Ettin is much easier to kill than quest at level 100+ i.e. dark bears, cyclops, succubus, balrocs.
More pro tips:
1) Use speed rare to reduce travel time.
2) Set up macro party (tank+heal+high level blaster) to help you kill Ettin. This is only for veteran players or people with friends to help them.
If you're already over level 100, Monster Hunt exp quest is still the best way to gain fame.
Be warned though, this is going to be a very boring process. Then again, nothing is fun when you grind.