Emotional appeal, as opposed to cognitive appeal, is more effective when the attitude you want to change is affective-based. Additionally, order of information in a message affects its persuasiveness. So, in a speech, it may be wise to state your main argument at the beginning and in a debate, it may help to be the first speaker. Finally, balance of information can be important in an argument. Under certain circumstances, it is more effective to mention both sides of an argument than to only mention one side.
Variables related to the receiver also have a bearing on the effectiveness of persuasion.
The most influential variables seem to be whether or not a receiver has forewarning and the disconfirmation bias of a receiver. If a receiver is forewarned about a persuasive effort, they are often more skeptical and arguments have lesser impact. Also, though this may seem like common sense, it is important to point out that the greater the discrepancy between the receiver's initial position and the position advocated by the message, the less persuasive the message will be. Some messages are so contradictory to the receiver's initial attitude that they are outside of the receiver's latitude of acceptance, or range of potentially acceptable positions, in which case they are hardly even considered.