How to set fee for a BitCoin transaction

To make a bitcoin transaction successful, one need to set a transaction fee. This transaction fee goes to the miners who verify/certify the transaction to make it permanent. If one gives low transaction fee, the transaction will take ages to get confirmed or worst case might never go through and if one gives higher than what it is required, (s)he is loosing money. So the real question which every user faces is how much fee to set for each transaction?

Transaction fee is measured in sat/b. The actual cost will depend on the size of the block and type of transaction. Below are few ways to determine best possible lowest transaction fee:

Blockchain Wallet
Blockchain wallet has a feature which decides automatically based on the status of the current mining of the blocks and determines the fee that one needs to set for the transaction to be successful. This is best feature for a newbie or a person who doesn't like to get much into details. It gives an option for the users to change the fee as well, with Customize fee option.

The default option is Regular (Reg) which will take more time but the transaction will be confirmed. Priority means the transaction will confirmed sooner. One can choose any value between these values to me more confident about the confirmation of their transaction.
bitcoinfees.21.co
Bitcoinfees.21.co, has real time information of the transactions that are being processed with respect to their corresponding transaction fee. From this graph one can deduce the time taken by a transaction to be successful based on the transaction fee.

Below their real time graph they also indicate a price with which one can get fastest confirmation with lowest price. The corresponding value in the above shared picture is 130 sat/byte. One will be better off even with using half of what is shown here, as the transaction will be confirmed with a time delay.
Manual way to determine the best and lowest transaction fee is to utilize Blockchain.info, to view the latest mined block. On the landing page, one can see all the transactions associated to that block. Scroll down and click through few transactions to make an observation on the transaction fee. One can set a transaction fee nearby those values for a successful transaction. This is more of a trail and error method and needs to be done on practice with patience.

These are the ways that use to determine the transaction fee to make a bitcoin transaction, if you are aware of any better method to do the same, let me know in the comments.