What is the best method for strong timber wall inside tin shed
Your sketch is more or less what I pictured. I'd make a few adjustments:


The primary stress will be at the points where the diagonals connect to the end studs. The entire horizontal load vector of the wall's contents is supported there. I'd double the end studs. 
Bring those connections up to at least half the wall height. I'd even go to 2/3 to reduce the bending load on the end studs. 
The top plate has to carry the horizontal load of the center portion of the wall's contents outward to the end studs. I'd double that, too. Maybe consider a 2x6 or 2x8 up there for stiffness. 


That's really it. As long as the bottom ends of the diagonals are slightly further from the wall than the center of gravity of the wall's contents, you should be dandy. Don't go crazy mounting it all to the floor. Friction will do most of the work.