From my experience, designing a lesson for one student could be challenging due to not being able to include group or pair-work, which is not only a great way for the students to apply what they have just learned with a fellow classmate allowing them to feel more comfortable to make mistakes but also gives the teacher the opportunity to walk around and listen in and find common errors that can be brought up to the class as a whole instead of singling out a single student's mistake possibly discouraging them, but also because after some time the student can easily get bored deterring them from fully learning the material the tutor is teaching. Here are five things I include in each lesson to ensure that the student is actively learning and having a fun time doing so as well.
1) Make your first lesson informal so they feel comfortable with you from the get-go. They will be hesitant until they feel it is okay to mistakes and the sooner you can get them to let their guard down the sooner you will be able to correct their mistakes and progress their learning more quickly and efficiently. Take this time to get to know them well. Learn where they are from and what their hobbies are and ask them why they desire to learn the language - most have a specific goal in mind other than learning the language for fun. A student who needs the language for work will have different lessons than a student learning the language to pass an exam.
2) Design each lesson as specific as possible for the student. Make sure the materials you use apply to the student's interest. For example, if they are learning English for work, use books like Market reader, have them do activities that are related to Business English, give them vocabulary that applies jobs, practice using realia that could include watching videos showing a work environment, role play phone conversations, interviews, meetings, negotiating - the more you know your student the better you can construct a lesson. A student who has just moved here and is looking for employment may need help writing a resume - not only will they learn the material you teach them but they will end up having something valuable to use in their real life. Learn the exams - TOEFL, IELTS, TOEIC, Cambridge, are the common English proficiency exams - and provide them with work that applies to just that.
3) Create themes for each lesson according to the student's interest. If they are into sports, have a lesson using articles on their favorite players, have them discuss the rules of the game and explain why they have a passion for it, ask them to write a page about a personal experience they had, doing so will show them you have interest in them as well as keep their interest because it is something they either like to do or talk about and will surely want to be able to do so using English - a soccer fan will enjoy being able to explain the game to some one, or go to a pub and catch a game and socialize with other English speakers about what is going on. When you run out of themes created from their hobbies, use themes that apply universally, such as illnesses and medical practices, learning our legal and judicial system, and if you feel comfortable enough with the student, the topic of politics, religion, and sex always provide interesting dialogues filled with vocabulary and expression.
4) While your lessons should have a structure to which they can become accustomed to, make sure you do not rely on a few types of activities because they will become bored if each grammar structure is taught only with fill in the blanks, or new vocabulary is only reinforced with with matching handouts, and try to not give any reading assignments because they can do that at home without you. For speaking, have them call places to make reservations and obtain information; for listening, have them listen to songs with a handout of the lyrics only with blanks to fill in; for reading, always use short texts such as newspaper articles that are not only topical and always changing inherently, which will keep them up to date with what is happening in the world; for writing, you can use craigslist and have them respond to ads they find interesting through email or even have them post their own ad. While it is necessary to use activities such as fill in the blanks to reinforce newly learned material, creating activities that allows the student to apply this material in real life settings is very effective in cementing what they learned and boosting their confidence, and your lesson will prove to keep their interest because the activities change accordingly with each student.
5) If possible, change the location of where your tutoring sessions usually are conducted. Have them practice the language going shopping at a grocery store with a list of things to acquire for a grand Thanksgiving dinner, there are museums that offer free admission and guides where the student can take notes and then have a discussion about their experience with you after, or perhaps have a whole lesson walking through places like South Beach where there are a variety of things to see and talk about and give them a chance to ask questions, at the end you can even give them a homework assignment where they write a letter to a family member or a friend about their outings, which you can use as a way to correct their grammar with the different tenses they are forced to use, give them new vocabulary for better details, and encourage creating more complex sentences - the student will feel happy when they send out their corrected letters.
There are so many activities that are not found in common ESL Books that is silly to rely solely on them or even worse, going through its chapters chronologically, which will almost always waste time with material they have already covered and mastered. Also, the more fun the student has with your lessons the more fun you will have teaching them as well.