Build custom oracle and use it from smart contract

bunjee

Hi,

I started developing a small dapp and I would like to check if a process is running from the smart contract and if yes, then execute something.
I found out that I need oracles in order to fetch some external data to the smart contract.

Although, I have the following questions/concerns:
1) Is there a tutorial on how to develop my custom oracle and how to use it in a smart contract?
2) Is it a good idea to use implement an oracle myself and use it? How oracles build trust to the users?

Thanks!

EDIT
I don't want to use Oraclize.it since I want to fetch my own data.