How can I make special symbols on my Samsung Galaxy SII, like ☺ or ♥?
These are actually Unicode characters you can easily reproduce on your computer: How can I get “WHITE SMILING FACE (U+263A)” with the keyboard?
The Android platform supports unicode and all its characters, however the soft keyboard that comes with your Android ROM probably won't carry all your desired symbols.
When long clicking on some symbols/characters on your soft keyboard you will see the key pop-up expanding to give you an additional choice of symbols, then drag and release your finger to print them.
Installing some 3rd party keyboards (such as GO-Keyboard) will give you access to more symbols.
I'm (still) using the average ICS (4.0.4) on a Motorola Atrix 2. If I go to the Symbols keyboards in the Standard Motorola keyboard input, and long press any symbol key, it will display a blue rectangle, showing the symbol, and whether there are other symbols available from that key. This is initially shown by an ellipsis (three dots: ...) to the bottom right of the symbol. If there are no other symbols, no ellipsis appears... Wait a bit longer and the other symbols will then be displayed in a new blue rectangle. Simply slide to the symbol you want. Most of the useful symbols are on the Second symbols keyboard, so press the [?123] key, then the [=\<] key, and Yes, the Heart (admittedly a black one) is under the • key.
For new versions of Android, the easiest way I have found is to use Character Pad - Symbols. It allows to add characters by
Simply tap a character to copy it to your device's clipboard, open any other app, and paste it anywhere you like
It also has a search function to allow finding characters by their names.
Disclaimer: I am just a user of the app.