and my farming is 11. What is the easiest way to level it up?

Farm.

 

 

 

 

 

 

 

 

 

 

 

 

 

Trees, Fruit trees, and herbs. Until then, it's easy and pretty straightforward...

If your farming is your lowest stats, try "pumping" it up with Tears of Guthix.

 

 

 

Also join a Clan Chat on finding penguins, it is quite fast to find all 10. Use the reward to gain farming exp.

 

 

 

On top of it try completing achievement diarys and use the exp lamp or doing stufts that gives you exp lamp.

 

 

 

While doing this, farm some fruit trees and trees. All this are relatively fast farming exp, but very short term solution as I see that you only wanted 25 Farming.