There are no safe paths.
In the mythical imagination of North-west Europe, forests were places of danger, confusion, and overwhelming wildness: places where Man was yet to establish his will and dominion. They were to be feared.
Mirkwood is dark, dangerous, & difficult.
In Middle-earth, while the wild-woods are beloved by Elves and Ents, they remain seas of danger and mystery to Men, Dwarves, and Hobbits. And among the forests, the greatest, darkest, and most intimidating was Mirkwood.
To have proverbs devoted to this great forest therefore makes sense. The ancient Dwarves had built a road crossing it, but in latter days it represented an impenetrable barrier filled with evil things. Even the small path of the Wood-elves represented little more than a tightrope across an abyss.
To successfully cross Mirkwood, therefore, required more than just good preparation; it needed enormous good fortune.
Depend on your luck & your courage.
Since the return of Sauron to Dol Guldur in southern Mirkwood, his malevolent influence had spread. Not only did the vast scale and darkness of the forest stand against the traveller, but there was also an enchanted stream and monstrous spiders (amongst other evil creatures).
Near the edge of Mirkwood... take the word of no one that you [do] not know as well as your brother or better.