I cannot find anywhere if players start the game with a standing score, and if so what it would be. So in that case I would assume that players start without a rating and have to raise it. (Adventurers rising from relative obscurity etc) have I missed it or am I misinterpreting the book?

"Adventurers start their career
with no rank in Standing."

AB, 117

You can raise standing with treasure and I think there are some rewards and virtues.

I've considered raising standing for extremely beneficial and heroic acts that help one's culture but I have not done it yet.

Ah! Thank you so much! I couldn't find it for looking. I'd second guessed myself from the lore masters' book with the way something was said, thanks for clarifying !

Remember the definition of Standing (AB 24): A character’s Standing score represents the respectability, acclaim or prestige he enjoys as a member of his community. It measures the character’s ability to participate in or influence the shaping of his culture’s history.

Standing is not a Renown or Fame score to be used universally. Rather, it is something to measure how he is received among his own folk. AB 117 explains this very well.

Here is how Standing is used...

1. During the Loremaster's Year's End narration, a hero with a Standing score can use a player-hero intervention to elaborate on the narration, testifying about his influence on events that take place in his homeland. The intervention must be proportionate with his score and he can propose a task roll to see if he succeeds. (AB 174)

2. During encounters, "The highest Standing value among those of any companions belonging to the same cultural group of the encountered party is added to the basic Tolerance rating for the encounter." (LB 53)

Here are some ways that Standing rank can be affected...

1. The Barding Cultural Virtue: Birthright prevents Standing rank from decreasing during a Fellowship phase. (AB 124)

2. During a Year's end Fellowship phase, a hero must spend time at home or he is required to spend Treasure points equal to his current Standing rank or he must decrease it by 1. (AB 169)

3. The 'Raise Standing' undertaking allows heroes to spend Treasure points to increase their Standing rank. (AB 173)

4. Companies must have at least one member with Valour 3 or at least one member who is a Beorning or Woodman with a Standing score of at least 1 in order to make Beorn a patron. (LB 113)

5. Companies must have at least one member with Wisdom 3 or at least one member who is a Beorning or Woodman with a Standing score of at least 1 in order to make Radagast a patron. (LB 116)

6. If a hero receives the title 'Burgess' of Lake-town, his Standing rank now measures his repute in the city of Esgaroth. When he spends a Fellowship phase in Lake-town, his score is not reduced, even though he is away from home. (LS 14)