As
@Barbarian has noted, a flat stone is a good stone - except for multiple recurve blades - a puck or stick may be required to follow the original grind lines properly without dulling already sharp edges - but that's an issue for later.
I too am a fan of the Norton Crystallon stones - I use a grey/orange (Med/Fine, 600/800 grit - with food/pharmacopeia grade mineral oil for lifting) two faced stone for edging, then a Suehiro 1200 grit manufactured waterstone for initial polish, then finish on a bench strop impregnated with green (1800 or 2000 grit) polishing compound. Keep some unfinished poplar, pine or other softwood around to de-burr the edge too.
Make or buy a good, stable, bullet proof stand for your initial cutting stones. You use more pressure on them than in polishing, and it gets you enough stand off that you are able to keep a good angle on the stone.
Use the whole face of the stones for sharpening/polishing - better wear patterns and better accuracy for keeping to the angles.
Don't worry about the slurry, even if it's black, as it builds it ends up being the same grit as the friable material and makes your job easier.
Clean and inspect your stones regularly - especially if you've sharpened a knife of suspicious quality (you'll know, it won't get a good edge, no matter how hard you work - mild steel or large grain 'cheap' steel are the main culprits. Use different stones for super hard tool steels like milling blades, they will need much more maintenance.
Don't discount the use of diamond impregnated sharpeners - but buy very high quality ones - and only use them for recutting edges, tips and shaping - they take off a LOT of steel and leave a saw edge that can be a bear to sharpen out and polish, especially on large grain loose matrix steels.
Invest in a quality magnifier or two or three - a couple of magnifying glasses in various powers, and I like a jeweler's loupe in 10x and 15x. Next purchase is a jeweler's/machinists lighted work magnifier.
Know your tools, do not lend them out unless you confident that the borrower knows what the deal is - or can pay to replace anything that gets damaged - a lot of people balk and scream "You want me to pay HOW much for a friggin rock?" ..at which point you are justified punching them in the face. (example - $50-$100 is a good median range for quality carborundum stones, high quality Japanese water stones only go up from the high end). You can also remind that person what they paid for the adjustable locking torque wrench they just bought... and will use twice a year, maybe.
While on 'vacation' I was sharpening 3-5 knives a day for others... various qualities, and got results from damn near perfect to this crap won't hold an edge to my standard. Remind people of this fact - 'presentation' knives are generally not working tools, they're pretty, but leave them on the walls, because they will not hold an edge ( unless the presenter and the recipient are knife geeks). Let people know issues right after your initial inspection of the blade as discussed earlier in the thread, and temper their expectations then.
And back to the knifemaker....