I get what you mean. what is important is that you first make sure you are really at comfort. If you have any troubles nagging or anything else that has great influence on your moods you won't be able experiment with this. So make sure you are happy, satisfied with yourself and comfortable in general.
To start off I wouldn't recommend looking for things that make you happy, sad or afraid. Just let those things naturally occur, be aware of how those feelings are. What it does to you, try to understsnd yourself and try to find reasons how and why this emotion happens.
You can and will never be able to completely 'remove' those emotions. Emotions are something that comes out of instinct and it's something that will always occur. What you can do is suppress it, though as someone else said it generally won't really dissappear. Surpressing is also a form of not accepting the emotion. Or you could accept the feeling. Let it inside and learn to act/deal appropiately to it. So say you are really happy and you want to jump around and scream.
Instead, sit calmly, breath in and out naturally and slowly to calm yourself and let the emotion run through your body. Observe the feeling and deal with it in the calmest way you can. This way you'll get control over your emotions. Side note: generally the older you get the easier it will be to control your emotions.
This also counts for fear and sadness.
With fear however, the easiest way to lost fear over somrthing is to not run away from it, but to confront it