Я бы написала следующим образом: Advantages of air travel: 1. Speed. For long trips such as transoceanic flights, air travel is the fastest way to get to your destination, but even on shorter trips plains are often quicker. 2. Safety.Plain crashes are extremely rare. According to the statistical evidence, air travel is more safe than automobile (for example). 3. Comfort. 4. Convenience. The process of buying plain tickets is very easy and convenient. (by telephone or by Internet). Disadvantages - 1. Price. Flying is often the most expensive form of transportation. 2. Some people have a fear flying because of the possibility of a fatal crash. 3. You cannot enjoy the scenery and changes in landscape.
Advantages of travelling by train. 1. Great views. You can see the beauty of different places. 2. Cost. Trip by train is often cheaper than buying an airline ticket. 3. Comfort. 4. Safety. 5. Flexibility. Trains often stop at major destinations en route to a final stop. You can choose any of numerous cities or towns along the way. (in contrast to plains which usually fly only to the big cities) Disadvantages - sometimes it takes a lot of time to get to your destination. 6. Trains are sometimes crowded.
Advantages of travelling by car - 1. You don` t have to waste your time and wait for a bus or train. You can go by car everywhere. You can plan your own trip, decide when and where you want to go. You don`t have to buy tickets, you only need a map or GPS system. Disadvantages - travelling by car is not very comfortable for driver, he cannot relax and he has to be carefull all the time. Venicles are forced to stay in traffic jams. Travelling by car is dangerous too. There are many crashes on the roads. Using a car is also pretty expensive. You need to pay money for petrol and services. Petrol prices are very high.
Как-то так. Можно еще добавить для интереса путешествия автостопом. Это опасно, долго, но зато можно увидеть много интересных мест и встретить интересных людей.
Удачи! Если будут вопросы, спрашивай!