Advantages and Disadvantages

Writing a composition is very hard sometimes, so I follow step by step. This is a very useful guide to write about advantages and disavantages.
Paragraths: introduction, advantages, disadvantages, conclusion and your opinion.
Expressions:
First of all, Firstly
Besides, In addition, Moreover, Futhermore
So, As a result, Therefore
However, On the other hand, In contrast
In conclusion, To sump up, On the whole.
One of the advantages/ disadvantages of... is..
There are advantages/ disadvantages to...
The main advantage of ... is..
A further advantages (of), problem (with) ...is..

 Cats are beautiful animals...if they want to be, so we have to know how cats are if we want to adopt one as a housepet.

One of the main advantages of cats is they are easy to care for, because they are trained to use the litter box. Besides cats can be left alone for a few days. Moreover cats are affectionate and they ask you to be petted. In addition you feel happy when they are purring in your lap.

On the other hand cats are used to scratching furnitures and sometimes they attack you for no reason. Furthermore if they are not neutred they can get into fights.

In conclusion cats are the best housepet, however you have your sofa fulls of cathairs.