How to install apps directly on SD card (HTC Wildfire S)

I have an old HTC Wildfire S recently updated with CM version 11. I am surprised to see how fast the phone is, and how this new system works very well.

Unfortunately, I have a severe problem due to the insufficient internal memory. I can actually move apps from my phone to the external SD, but this procedure doesn't allow to install huge apps. The point is that you have to install firstly on the phone, and only then you are allowed to move to the SD card - clearly if the phone hasn't enough memory just since the first step, there's nothing to do.

My answer is: how can I install apps directly on my SD card? I found A LOT of material googling, but all the articles seem confusing and not so safe. I have chosen to ask here just to be surer to obtain a wise answer.

Thank you in advance. Cheers

Ps: if it could solve easily the situation, I have no problem in downgrading to previous versions of CM.