Create a picture of what you really want
But before you ask, you have to know what exactly you want to receive! This is something that most people overlook when they aren't satisfied with current situation. They know that they need some kind of a change - but they don't know what exactly they want. In order to pull out good results, you can say that you are disapprove current situation - but you have to support your statement with your opinions, wishes and needs. Take your time and think about your needs. Create a clear picture of that and then proceed with changes. As we all know, no matter how bad situation is, change doesn't have to be positive.
Express your needs clearly
When you talk about what you really want, don't hesitate. Say it openly; "I want this, this and that!". Problems with a lot of people is that they believe they've clearly expressed themselves, while in reality they only said hints. And then even if others want to help you, they can't because they don't know what exactly you want. Another important thing is to speak by using "I statements". That way you give your words bigger meaning and increased importance.
Pick right time for conversation
Even though almost every moment can be good for starting that kind of conversation, there are some moments that should be avoided. For example, you shouldn't express your wishes shortly or during arguments or fights. That might give a different light to your opinions. You have to find perfect moment for expressing your feelings and needs.
So at the end, the point of all this is to have self confidence, and don't forget - ask to receive!