In my company I was facing a scenario where I had to chain two Apex asynchronous calls:
First I needed to call myApexMethod1 which returns a result myResult
Secondly I needed to call myApexMethod2 but needed to provide myResult as a parameter to the method.


So this is the first version I coded :
 

({
    "myFunction" : function(cmp) {


        var action = cmp.get("c.myApexMethod1");
        action.setCallback(this, function(response) {
            var state = response.getState();
            if (state === "SUCCESS") {
               myResult = response.getReturnValue();
            }
        });
        $A.enqueueAction(action);


        var action2 = cmp.get("c.myApexMethod2");
	action2.setParams({ myParam : myResult });
        action2.setCallback(this, function(response) {
            var state2 = response.getState();
            if (state2 === "SUCCESS") {
               //Do something
            }
        });
        $A.enqueueAction(action);


    }
})

This code compiles well but there is a problem:
Since the calls are asynchronous, by the time we reach :
action2.setParams({ myParam : myResult });

it is not guaranteed that myResult is filled, because at that time nothing guarantees that myApexMethod1 has executed since it is asynchronous.

To avoid this behaviour, I decided to nest the second call inside the callback of the first method.
That gives the following code :
 

({
    "myFunction" : function(cmp) {


        var action = cmp.get("c.myApexMethod1");
        action.setCallback(this, function(response) {
            var state = response.getState();
            if (state === "SUCCESS") {

               myResult = response.getReturnValue();

               var action2 = cmp.get("c.myApexMethod2");
	       action2.setParams({ myParam : myResult });
               action2.setCallback(this, function(response) {
                   var state2 = response.getState();
                   if (state2 === "SUCCESS") {
                        //Do something
                   }
               });
               $A.enqueueAction(action);

            }
        });
        $A.enqueueAction(action);

    }
})

I have tested it and it works.

But my question is:
Is it the proper way to chain these asynchronous calls?
Next time maybe I will have to chain a lot of asynchronous calls and this pattern does not look very clean?
Is there a better practice to chain these asynchronous calls?