If you are rich newbie with a lot of start-up funds, then you can afford to start with a premium WordPress theme, but that is not absolutely necessary. Free WordPress themes that are available with WordPress are perfectly suitable for start and it is possible to update your theme to a paid and premium theme in future without losing any content or settings.
What you should not be doing is to recklessly download free themes from shady internet sites. These themes have been poisoned with hard to locate links to seedy websites. By now we should be very clear that nothing comes free in this world, even on internet. There is a reason that these premium themes are being offered on these shady sites for free use.
It would be better that you choose a free theme from the ones already available from your WordPress dashboard. Go to Appearances> Themes and you will be able to preview hundreds of free themes to choose from after you click on Add New button.
These free themes can be sorted by filters like newest, Featured or Recently Updated. Or more specifically you can filter themes based on your choice like features, colors, columns and subject etc. However, there are a few important features you want to be there in your selected theme.
Unless your website is all about photography, you would be looking for themes where text is featured more than images, especially on the home page. While it gives a good appearance to have some images on home page but it should not be all about images for most of the websites.
Also you should stay away from a theme which has a very large header that takes up the entire space above the fold. This is the area that you before needing to scroll down to lower part of the page.
Ideally your above the fold area should have space for things like your header, navigation menu, the short snippet of your latest post, your sidebar with the optin form and freebie available above the fold without the visitor needing to scroll down.
So you might notice that the default Twenty-Eleven theme used to have huge header that would occupy the whole screen but its size has been reduced now in the latest default theme. It is also possible for you to upload your own theme.
Some of the newbies want to start an Amazon review site, therefore, they are mostly attracted to a specific review theme. It is perfectly fine to go with that theme unless it is not automatically pulling and copying text.
Success can only be possible if you create useful sites with unique content depicting your own personal style. Scraper sites that are pulling text from elsewhere are not going to take you anywhere. People have become smarter than before and do not trust scrapper sites. You might succeed in getting some traffic but the user would be able to instantaneously tell the different between content that has been scraped from one that has been written in a personalized way.