User blog comment:Mathmagician/Wall of Flesh Solo Guide/@comment-71.49.62.117-20120104203352/@comment-4674838-20120105000124

You're right, I haven't seen any guides about good ways to fight the Wyvern for the first time. Alright, I'll try putting one together. To give you the short and sweet version, I'd advise using Crystal Storm + sufficient number of health/mana potions + minimum of Cobalt Armor or maybe even Mythril Armor set for your core gear. Also going to want certain accessories such as Cobalt Shield (no knockback), Spectre Boots (running and flying) and something to prevent fall damage, ideally a Lucky Horseshoe, but grapple hook or cloud in a bottle, etc. could also work.

Other weapons such as Dao of Pow, Star Cannon and Adamantite Repeater can also be decent pre-Wyvern/Hardmode Boss weapons, but they aren't as practical and flexible in their usage. I most strongly recommend Crystal Storm. As for strategy, either use Gravitation Potions or build some sort of arena/skybridge in the sky. (You can log out and back in if the Wyvern spawns while you're building the arena and you're not ready to fight him yet.) Anyways yeah that's just my two cents. If you want you can wait for more of a complete guide, as I'll try to put one up by tomorrow.