AHA...unless you are willing to plunk down major moolah on filters, don't bother with the filters as the cheapo ones are just not worth it. I would rather use a lens hood and forget about the filter if the aim is to protect the lens. Remember this is an addition of another glass element in front of the lens and that will effect the PQ.
The picture on the right is much better from what I see...do remember that not all zoom/tele lenses are super at all focal lengths. The sweet spot for a 70-300 (usually a jack of all trades, master of not many) may be around the 150-210mm focal length. Your mileage may vary.
Now that you have the first issue taken care of, start looking into metering and more importantly lighting
Have fun, this is a great hobby with rewards. Take thousands of pictures and don't be afriad to experiment.