Hi pnj.robinson20,
The best way and place to start is with what you know. What do your elders, parents, grandparents, aunts and uncles have to say about your family ancestry? Then, start to collect birth, marriage and death certificates to find information on names and ancestors within these documents. Next, go to websites such as the UK's freeBMD website and see if your ancestors come up in the searches, as well as the familysearch.org website. This is a good start to find enough to begin a tree.
I started with with my parents and grandparents. Then I went to the State of Hawai'i Department of Health to obtain birth, marriage and death certificates. My mother's birth certificate had her parents, then I located my grandmother's birth certificate, which had her parents, my great grandparents, then I researched sites that showed who my great great grandparents were. From there, I spoke to elders who told me who my great, great, great grandparents were. I also did a lot of research via the internet, and contacted the UK GRO and BMD through their website. I requested and paid for birth, death and/or marriage certificates of my British ancestors via the mail. Then I searched on Canadian sites, primarily in British Columbia. Some of my ancestry is already done by other people also descended from the same people, of long, long ago.
Another method, that surprisingly does work for some ancestors, is simply "googling" the names of your ancestors and see what comes up. You might be surprised to see who else out there shares the same ancestors as you.
Also, always be a bit wary, if not skeptical of what information you obtain via the internet, if it is not from thoroughly researched and published sources or from say the UKGRO or BMD sites, vital statisitics, census and registries that are authentic. I have found much of my long ago English ancestry on the familysearch.org site, and much of it is valid, however I know some of it is not. So I have corrected those inaccuracies. Also, there are various genealogical publishing and book research sites, via the internet, that actually have books published on ancestry. I have a few books of some of my ancestors.
I hope this helps! Good luck and happy digging for you genealogical past and ancestral trees.
Sincerely yours, Keanani