There are a few different answers to your question. I've been sharpening for the last 10+ years and I own an Edge Pro, A Wicked Edge, a Spyderco Sharpmaker, a Lansky and a Slicing Edge Sharpening System that consists of ( 2 ) 8" Paper Wheels. And hopefully in the near future I'll have a Tormek T8 with the Japanese water stone addition!
I don't have much freehand experience but I do have lots of guided system sharpening experience.
With that said:
1: eye protection (when working with the paper wheels)
2: some gloves, nothing too heavy just something to protect you (when working with the paper wheels)
3: remember to always put some marker on your edge to make sure you have the correct angle (i use red dry erase marker for better visability)
4: If you don't have a slight burr opposite the side you are working... you ain't done! Keep going slowly and lightly until you get that burr.
5: invest in a 5x or 10x loupe (it's amazing how often you won't be hitting the actual edge you think you are hitting)
The absolute fastest and most versatile are the Paper Wheels $27 online. You mount them on a $50 harbor freight grinder and you're off to the races. One wheel is a does the actual sharpening and the other is a polisher. You do (literally) 3 to 5 light passes on each side for the sharpening wheel and about 5-10 passes per side on the polishing wheel. Lots of youtube vids on this, I bought them, didn't think they'd work but I'm a believer... they work nicely and give you a hair popping edge with very little practice. Touch ups are super easy and even faster. The only cons are, it's not very portable and you have to be super attentive (no distractions) when you are working with a spinning wheel and a blade edge.
The Wicked Edge is easy and straight forward, will always give you the edge you set it for but it's expensive. It's totally idiot proof! I should know
Sharpmaker is the absolute easiest and will give you a good edge but it can take a long while if you are removing stock from an edge. God help you if it's a thick edge. I only use mine for touch ups.
That brings us to the Edge Pro. Mine was on a shelf for the longest time, the stones were concave, I broke the plastic trim on the guide and I never really got my edges to "Pop". I always had trouble keeping the knife flat and it (I) would always change angle slightly by not applying even pressure to hold the knife down.... which would give me an uneven profile.
I took the time, leveled all of my stones, ordered the guide plastic (3 for $1 from Edge Pro) and did the best mod I could ever do to it..... I picked up a 1/2 inch cube magnet from KJMAGNETICS $5. Holy hell, this little 1/2 inch cube has 18 lbs of pull! I put it just underneath the plastic where your knife would rest on the Edge Pro (hot glued it). Best Mod Ever! Holds the knife down very well and makes using the Edge Pro much faster, safer and much much easier. Edge Pro sells a magnet kit on their website for $25 that does the same thing.
Another mod you can use for the Edge Pro... Harbor Freight sells 3 flat (separate) diamond hone blocks (course, med, fine) for about $10. You can use these on your Edge Pro! They fit! They cut metal stock pretty quickly and are great for kitchen knives because they are 2 inches wide, they don't flex either. Super nice if you don't want to dirty up your stones with high carbon kitchen knife steel.
So to make my life easier, I sharpen almost everything at 20 deg per side. Wicked Edge, Edge Pro, Paper Wheels. Then when they need a touch up, I use the 40 deg Sharpmaker setting. The trick is to get them shaving sharp with the brown stones and then hit them for a few passes on the white (fine stones).