Well, an interesting question indeed!
The best way to remember a password is to let the browser of your device remember it. Now, if your device is shared with other people, then it may create a problem if you want to keep certain things private in that account. To prevent other persons from accessing your account on a shared device, where the password is saved in the browser, one needs a bit of extra work - first allow the browser to save your password, then change your password. Change just the last character of your password saved in your browser. when you log in the next time, let the browser auto-fill the password, then delete the last character and type in the new character and log in. Here is an example - suppose my password for Snapdeal is 'Snapdeal@1', firstly I will allow my browser to save this password, then I will change the password to 'Snapdeal@2' (replacing the last digit -1 with 2. I will again try to login at Snapdeal. The browser will auto fill the old password (Snapdeal@1), I will delete the last character ('1' in this case) and type in '2'. Then I will hit the submit button. The browser will try to update my new password for Snapdeal, which I would not allow my browser to do.
One needs to understand that all the secured sites recommend a minimum eight character password, with at least one character as a capital letter, one digit and one special character. So, the most basic password can be a six -letter word (with the first letter of the word in caps) with a digit and a special character. Like in your case
a) for amazon - Amazon@1
b) for snapdeal - Snapdeal@1
c) for naaptol - Naaptol@1
These passwords are easy to remember, but are easy to guess too. Now to make this a bit more difficult, one should not write the first letter of the word in caps. Instaed, one can select say the third or fourth letter as capital letter, replace the special character '@' with an uncommon character like carrot (^ uppercase of 6 on a keyboard), followed by a 3 or 4 digit number from our past (should not be related to our DOB, house number, present vehicle number, etc), say I select 1735. Now, your passwords would be something like this
a) for amazon - amaZon^1735
b) for snapdeal - snaPdeal^1735
c) for naaptol - naaPtol^1735
Now if you regularly type these passwords on your mobile, it will throw them up whenever you try to log in. To avoid that you can again add an extra special character, like inverted commas - " - at the beggining of the password. So, now the passwords look like
a) for amazon - "amaZon^1735
b) for snapdeal - "snaPdeal^1735
c) for naaptol - "naaPtol^1735
These are strong passwords. You can make them even stronger by repeating them but with different special characters or by reversing the position of special characters.
When you talk, you are only repeating what you already know. But if you listen, you may learn something new!