For a beginner, there are several authors I would suggest avoiding purely because they perpetuate negative mindsets into the community at large, that become very difficult to have a high number of people to unlearn.
For instance, many beginner books on Wicca continue to hold the idea that the words witchcraft and Wicca are interchangeable, when in fact this isn't true. Witchcraft, at its core, is a nonreligious practice that can be applied to religions. By directly equating it to Wicca, one is saying that witchcraft is inherently religious.
Books also like to take practices and ideas from closed cultures and religions. Native and indigenous faiths are, more often than not, closed to outsiders by request and decision of higher ups within the culture, this includes Azteca and Mayan faiths and the practice of smudging, creating dream catchers, and use of the term spirit animal or animal totem as these all have specific religious connotations that are frequently devolved to an unrecognizable form by outsiders. Cultural appropriation is considered a form of racism.
Many popular authors also like to conflate deities from separate mythologies or to use deities in the most base form possible. Deities are complex and often times have multiple associations, and they cannot be conflated with other deities when trying to convey historical information. Greek deities are not the same as Roman deities. Celtic is actually a massive umbrella term encompassing deities and practices from regions all over Europe. Isis is actually a Hellenistic deity and not Egyptian, her commonly ascribed counterpart being Aset. This conflation subtracts from the meaning of gods and myths, and makes for a difficult time to have academic discussions.
A lot of books are also prone to some form of direct discrimination, be it towards Christians or other Abrahamic faiths, the LGBTQIA+ communities, or even certain races and ethnicities. This poses the moral question of "Why have they become popular?"
Some authors that should probably be avoided:
Christopher Penczak - His "historical" information regarding the history of witchcraft is incorrect, he appropriates deities and practices from closed cultures, and he conflates or over simplifies deities in many of his works.
Lupa - She is prone to using appropriative terminology and has worked with other problematic authors in the past (even as recently as 2013 and 2014). Her blatant disregard to the perpetual use of totem being offensive to many indigenous cultures is incredibly racist.
DJ Conway - Her books contain false history, when they do include it, primarily in regards to Celtic and Norse topics. The Celtic peoples were not one people, and trying to write them off as a singular people is historically inaccurate. Celtic was a word applied to Britons by the Romans meaning warrior and it has been used by archaeologists to describe Gaels, Britons, Welsh, Gaulish, Gaul-Germanic, and Celtiberian peoples, all of which had separate cultures, mythologies, and histories. She has two fairly popular books on the Celts regarding shamanistic or magical practices, which are inherently wrong. Shaman is a word taken from indigenous Siberian peoples and should never be applied to European faiths, first off.
Edain McCoy - Probably one of the biggest offenders out there, using a combination of made up history, falsified history, and appropriative terms. This author became so well known for their misinformation among many online circles that there was even a campaign launched to try and end the misinformation and blatant disrespect of those books. (Google Stop Edain McCoy for more information.)
Raymond Buckland - This author really loves to swim in historical inaccuracies. His book on "Scottish" witchcraft declares that the ancient Picts practiced Wicca and he also has a book on "g*psy" magic that is a disgusting and inaccurate "representation" of the cultures slurred with the word g*ypsy. He would not be a good resource for beginners. Additionally, there is also the issue that he revealed coven secrets, information he would have been oath-bound to maintain the secrecy of. This is very offensive in general.
There are most definitely other authors to avoid, however these are the ones I've most recently seen recommended to large numbers of people.