I don’t have any better free pattern suggestions than what Jints listed (great patterns, btw!) but I wanted to put a plug in for choosing a pattern that is worked in the round. I wish I had started making sweaters in the round instead of in pieces at first – not having to seam pieces together is so much easier (IMO.)
I also wanted to mention that when you do get to the point where you want to invest in a good book for sweater making you should consider looking into the many books by Elizabeth Zimmerman.
Her style of writing patterns takes a little getting used to but armed with her knowledge of how sweaters go together and her percentage system which will allow you to make sweaters in all sizes and with a great selection of gauges, your sweater making possibilities will be almost endless.
Where many knitting books are limited to just the specific patterns featured done in a limited choice of yarns, EZ’s books encourage you to test the limits of the pattern and add your own creativity to the mix.
The Sweater Workshop by Jacquline Fee is another good choice.
Have fun choosing which pattern to make!