Family history work can be fun and exciting-- even for beginners, as I found out earlier this year.
A great place to start is by registering for an account on the New Family Search website, associated with the Church of Jesus Christ of Latter-day Saints. You do not have to be LDS (Mormon) to join! It is really easy to input the information you do know, and it is likely that if you get a few generations back, you will connect with lines on which a lot of research has been done.
If you are looking to find records to back up what you think you know about some of your ancestors, the Church has another great resource: the Family Search website. If you're lucky, you will find census records, marriage certificates, and other documents, with links to actual images of the original documents-- like this -- for free. The Perrens, shown at that link, are actually some of my ancestors.
The information available at Family Search has been indexed by volunteers, and if you are looking for a great way to spend some time, you can volunteer, too. It's fun, especially if you are fascinated with old-time artifacts and like puzzles. Sometimes the handwriting and spelling on those census records is quite challenging to read! The different indexing projects are sorted according to difficulty.
If a lot of the foundation work has been laid by dedicated genealogists in your family, don't get discouraged-- there is still work to be done. Thomas' grandmother was one of those dedicated genealogists, but we discovered just this week that there is some transcription work to be done. We will be working on getting some family journals typed up and into an easily-accessible, searchable format. If you don't know of any opportunities like that in your own family, see if your friends need help with theirs.
If you are still too afraid to start, make the work easier for future generations by keeping your own records-- and keeping them organized. Keep a journal and try to organize and label your pictures.
Preserving family history helps people to know who they are, and family history work, with temple work intimately intertwined, preserves families for eternity!