There are several factors that directly impact your effectiveness here, for example, do you even have the skill to get you through the experience effectively? If you do not actually have the skill yet you attempt to cross a mine field you will probably blow up. If you actually don't know what to say or how to act or you don't know how you should behave to achieve your objectives you won't really know what works in your situation, will you?
Something that can really reduce your effectiveness is worry thoughts. Worry thoughts get in the way of your ability to act effectively. You have the ability, but your worry thoughts interfere with doing or saying what you want. You may worry about bad consequences, "They won't like me," or "She will think I am stupid". You may worry about whether you deserve to get what you want; "I am such a bad person, I don't deserve this." Finally, your worry thoughts may be about not being effective or calling yourself names; "I won't do it right," "I'll probably fall apart," "or, "I'm stupid."
At times your emotions can be the show stopper to effective choices. Your emotions (ANGER, FRUSTRATION, FEAR, GUILT) get in the way of your ability to act effectively. You have the ability, but your emotions make you unable to do or say what you want. Emotions, instead of skill, control what you say and do.
Here is one that I personally find as an ingredient when I haven't been effective, indecision. You can't decide what to do or what you really want, your objective isn't clear. You have the ability, but your indecision gets in the way of doing or saying what you want. You are ambivalent about your priorities. You can't figure out how to balance: