We were in your situation about a year ago.
Regarding wasters: opinions vary. <img src="/forum/images/icons/smile.gif" alt="" /> We have a pair of Purpleheart wasters that we are quite attached to, though many here don't like Purpleheart much. We also have a pair from Wooden Weapons, which we are not so fond of - they are heavier and clunkier. [Though that makes them good for handing for local kids who are watching our driveway practice sessions.... <img src="/forum/images/icons/smile.gif" alt="" /> ] I found Wooden Wasters' customer service to be very poor - they were awful at responding to email or phone calls.
Regarding manuals: don't get one - get several. None are perfect; the three I'll list below [which are the three we have] each have strengths and weaknesses. If you have more than one, then you can cross-compare when one of them confuses you - which, if you're like us, they will. <img src="/forum/images/icons/smile.gif" alt="" />
John Clements'
Medieval Swordsmanship gives a good introduction, and it covers more than just longsword, including a solid chunk of background material on history and swords. It uses very spare drawings of techniques.
Lindholm & Svard's
Knightly Art of the Longsword directly translates and comments Ringeck.
On the one hand, this means you get things straight from the source, and the diagrams show footwork; however, we periodically find ourselves disagreeing on how a technique should be executed because the diagrams aren't always clear; and the original text is often cryptic - good for making you think, not so good for being clear (and the book's own commentaries do help there).
We've recently picked up Tobler's
Fighting with the German Longsword is written with step-by-step building on techniques in mind. There's a lot of helpful text explaining what's going on. Pictures display techniques; the pictures are clear (good) but it isn't always clear how you get from A to B to C (bad). Tobler also includes drills, which are useful of themselves and as starting points for modification as a means of practice; some of these we'd come up with on our own, many we had not.
Find a training partner, too. Best training aid in existence. <img src="/forum/images/icons/smile.gif" alt="" />