As we know Android cannot run programs from the memory card and therefore all the applications have to be located in the rom memory. This is true in the official versions, but there are versions of rom in which the programs, and even the cache used by various applications, can be transferred to the card and continue to function normally.
What do we need? Well, a Micro Sd card of up to 32 GB minimum of Class 4 (a class 6 recommended), a program to create partitions on the card and a program to format the card with EXT2 or EXT3 format and Linux Swap.
What strange things does this guy say, right? Don't worry, it's simple, I've even done it. Go for it.
The card has to be a MicroSd of up to 32 GB of capacity and a minimum of Class 4 but preferably class 6. There are class 4 and 6, the larger the number, the faster the data transfer speed between the card and the phone.
A program to make partitions on the card. Partition Magic or Paragon Partition are two paid programs, but you can go through softonic.com and look at the free ones.
Once we have the appropriate program we must create three PRIMARY partitions on the card. The first of the capacity we want, the second cannot be greater than 1,5 Gb and the third of 32Mb.
Now it's time for the most complicated.
We have to format the three partitions, one as FAT32, another as EXT2 or EXT3 and the third as LINUX SWAP.
For this we have to have a Linux distribution. You can download the one you want, I did it with a distribution Ubuntu. You download it, it's free and legal, and you record it on a cd. Then you have the option to run it directly from the CD or install it on the hard drive. The application to format in Linux is called Gparted.

As you can see in the image I have three partitions created and by clicking on each partition and giving the right button I can choose what type of partition to choose to format it. We do it for each partition and each one of the class discussed above, Fat32, Ext2 or Ext3 and Linux Swap the last one.
We already have the card ready to be able to pass the applications. This I will tell you in another manual that is almost finished.