Speaking logically means organizing your thoughts and ideas in a clear and coherent manner, and presenting them in a way that is easy for your audience to understand. Here are some tips to help you speak logically:

1. Plan your thoughts: Before you start speaking, take a moment to organize your thoughts and ideas. Make an outline of the main points you want to cover, and the order in which you want to present them.
2. Use clear and simple language: Avoid using complex vocabulary or jargon that your audience may not understand. Instead, use clear and simple language that is easy to follow.
3. Use evidence and examples: Use evidence and examples to support your points and make them more convincing.
4. Be concise: Be brief and to the point, avoid unnecessary detail and rambling.
5. Use transitions: Use words and phrases that help to connect your ideas and create a smooth flow of thought.
6. Use signposting: Signposting means using language to indicate the structure of your talk or the progression of ideas, for example: "First, I will discuss..., Next, I will talk about..., Finally, I will conclude with..."
7. Use rhetorical questions: Rhetorical questions can be a powerful tool for engaging your audience and encouraging them to think about your ideas.
8. Be logical: Follow a clear and logical sequence in your arguments and be consistent throughout your speech.
9. Be flexible: Be open to feedback, and be prepared to adjust your ideas or approach if necessary.

It's important to note that speaking logically also means adapting your language to your audience and the context, and being able to understand their perspective.

There are several factors that can affect one's ability to speak well. Some of these include:

1. Language proficiency: A speaker's level of proficiency in a language can greatly impact their ability to speak well. This includes knowledge of grammar, vocabulary, and idiomatic expressions.
2. Self-confidence: A speaker's level of self-confidence can greatly impact their ability to speak well. A speaker who is confident in their abilities is more likely to speak clearly and fluently, while a speaker who is uncertain of themselves may hesitate, stumble over their words, or become easily flustered.
3. Preparation: A speaker's level of preparation can greatly impact their ability to speak well. A well-prepared speaker will have a clear understanding of their topic, a well-organized outline, and will have practiced their delivery.
4. Audience: The audience plays a crucial role in how well a speaker speaks. The audience's level of understanding, interest and attention can affect the speaker's ability to communicate effectively.
5. Environment: The environment in which the speaker is speaking can also affect how well they speak. Factors such as noise level, lighting, and room layout can all impact a speaker's ability to communicate effectively.
6. Language context: The context in which the speaker is communicating can affect how well they speak. For example, a formal business presentation may require a different speaking style than a casual conversation with friends.
7. Nonverbal communication: Nonverbal cues such as facial expressions, gestures, and tone of voice can also affect how well a speaker communicates.
8. Emotion: Emotions can also have an impact on how well a speaker communicates. For example, a speaker who is anxious or stressed may find it difficult to speak clearly and fluently.

It's important to note that speaking well is a combination of many factors and it requires continuous practice and self-evaluation.