Depth of field reccomendation

[Rabbitman 30]

could you guys reccomend me the level of depth of field I should use? Like what blur size would you reccomend to make the blur not too strong but still y'know blur out stuff.

[FredMCGamer 649]

If you're getting into animating and nice wallpaper creating I recommend looking at this two YT channels:

Anxious Cynic: 

https://www.youtube.com/channel/UCgU96NeglbPZIfclA9C6GPQ

And last but not least:

https://www.youtube.com/channel/UCIcrA13YzojoPIa38xCjYIA