Implementing a leader board / high score (File read / write)

I need help implementing a leader board / high score in my game.

Any tips/suggestions?

As bonus help (:P), any ideas on how I can make this online (server stored leader board).

Try this

http://wiki.unity3d.com/index.php?title=Server_Side_Highscores

I think this will help you a lot.
LeaderBoard And HighScores.
I am using this from two months, its totally suits my requirements.
My requirements are same as yours.

check out this 2 and tell me if you like it.

Facebook version if you’re keen
https://www.assetstore.unity3d.com/en/#!/content/17803

Check out this one : GitHub - rankpin/rankpin: Free ranking service for Unity mobile game development

top/friends/weekly unity ranking system.

I’m using SOOMLA’s game backend, which works really for social leaderboards. Other options you have out there are Gamesparks, Gamedonia, Playfab and Heroic Labs. They are all heavily priced though once you break a certain threshold of MAU, and SOOMLA is completely free.

Hi!
If you are looking for a very easy way of creating a leaderboard or share data between various devices you may find Syncano useful. It allows to exchange data with only a few lines of code. Check out this blog post: https://www.syncano.io/blog/how-to-create-a-leaderboard-in-your-game-with-a-few-lines-of-code/

Cheers!

Hi!
If you are looking for a very easy way of creating a leaderboard or share data between various devices you may find Syncano useful. It allows to exchange data with only a few lines of code. Check out this blog post: https://www.syncano.io/blog/how-to-create-a-leaderboard-in-your-game-with-a-few-lines-of-code/

Cheers!