The number one thing you must do -
You will probably start your tree by jotting down what you know now. Your close family's names and dates of birth, and you will probably ring your mum or dad to check some of that information. When you do, have a column or box, or just a different coloured pen where you put the name of the person who gave you the information. If they go and look up a certificate, get a copy of that certificate!
There are two types of sources:
PRIMARY - records created at or near the time of an event by a person who had close or official knowledge of the event. These are things like birth death and marriage certificates or census records, often called vital records. Primary records are usually cited as giving almost certain authenticity to information. They are more reliable than secondary sources.
SECONDARY - records created a significant amount of time after an event occurred or by a person who was not present at the event. These are things like newspaper clippings, and family recollections. I would cite these as either possible or probable in terms of reliability.
But one source is not always enough, and you need to make a judgment a lot of the time about the authenticity and reliability of information. Funny enough, people lie about their age for instance - to sign up for the military, to get married, and just because they can. One of my ancestors even lied about their name; but more of that later. Knowing where information came from will be critical, trust me.
We will come back to sources and citations soon, but in the meantime, just get started, here is how.
Task # 1:
To start, get a piece of paper and write what you know about your family tree. Start with full names and dates and locations of births and deaths. In a different coloured pen put your initials next to each piece of information.
Then ask your partner and mum and dad for information, and do the same with their name or initials.
Later you will really need that information about who told you what and you will be saying 'thats gold'.
Your on your way to starting your family's genealogy - congratulations.