Most of what was written about Canaanite religion in antiquity was written against it, and that shapes the subject to this day.
The Hebrew Bible is the largest such body of evidence. It denounces Baal, Asherah and the high places at length, legislates against practices it ascribes to the peoples of the land, and narrates confrontations such as Elijah against the prophets of Baal. These texts establish that the cults existed, were attractive, and were practised by Israelites: a polemic sustained over centuries is aimed at something. They are not reliable on what those cults were for, or on how the people conducting them understood the matter, and the category of the Canaanite is itself partly a construction of these texts, an other against which Israel is defined.
Archaeology has complicated the picture from the other direction. Inscriptions found at Kuntillet Ajrud in the Sinai and at Khirbet el-Qom, dating to about the eighth century BCE, invoke blessing by Yahweh "and his asherah". Whether that phrase names a goddess or a cult object associated with her is debated, but it indicates that Israelite practice was less uniform than the biblical writers wanted, and that the boundary the Bible draws was being drawn precisely because it was not obvious on the ground.
The charge that follows the tradition hardest is child sacrifice. Biblical texts condemn the passing of children through fire to Molech; Greek and Roman authors accuse Carthage of sacrificing children; and excavation at Carthage and other Punic sites has uncovered walled precincts holding thousands of urns of cremated infants and young animals. Specialists disagree sharply about what this shows. Some read it as the practice the ancient sources describe. Others argue the precincts are cemeteries for infants who died naturally, in societies with very high infant mortality, and that the accusations are the standard rhetoric of hostile neighbours. Any account presenting either position as settled is overstating the evidence.