Effective Dragonriding does not look like a series of sine waves. That is what everybody tends to think when they first see it, but that is in fact a very inefficient way to use your Vigor.
Effective Dragonriding lools like a series of upward vertical lines with a half-catenary shaped glide.
Straight up. Then either a shallow glide just steep enough to maintain the 929% unpowered max, or a steep dive followed by levelling off.
Your armoury says that you have not yet collected alll the Dragonriding glyphs. You need to get all 6 charges before you judge. Flying with 6 charges and all talents is a very different experience to flying with 3. Especially, the very last talent “At Home Aloft”, that restores 1 Vigor every 5 seconds during Thrill of the Skies, is key. Without that, your Vigor is going to sputter and die like an engine that is out of petrol.
SO GET ALL GLYPHS NOW. There are many guides, both written on on YouTube, explaining how.
Honestly, I think Blizzard erred in making it necessary to fill all glyphs before you can really use Dragonriding. Yes, I get it, it provides a sense of progression. But it also provoked many first reactions like yours at the start of the expansion, and that wasn’t good.
At the start, your Dragonriding is more like walking, with the ability to fly up for a short distance.
Once you have all glyphs and applied all your talents, the way to Dragonride is:
Point straight UP with your right mouse button.
Use Skyward Ascent, two to four times in a row, with about 2 seconds between presses to allow Thrill of the Skies to have its full duration for each flap. Skyward Ascent always gives you about 2 seconds of Thrill of the Skies.
As soon as your Thrill of the Skies turns off on your last flap, quickly point either slightly down for a very shallow dive, or very steeply down to gain momentum, and then levelling out.
Watch your Vigor recharge, and repeat when it is almost full again.
“Thrill of the Skies” is the talent that recharges 1 Vigor every 5 seconds. It is key to Dragonriding. You can see it in the Blue Glow around you when at max speed, or immediately after pressing Skyward Ascent. By letting each Thrill have its full duration, you will find that after using say three Vigor, you will have lost only 2, because you regained one during the Thrill.
Personally, I use this WeakAura for a visual indication of my speed and Thrill status:
It is not necessary, but that blue glow can be hard to discern accurately, and it is great to see that reassuring 929% on the speed indicator telling me that I don’t need to nose down any further.
You will probably not use any of the other Dragonriding abilities in normal flight, just during the races.
P.S. A thought struck me as I was writing this, so I went to check.
I flew from Valdrakken to Iskaara in one hop. I took off from Valdrakken beside the Flight Master. (Starting from the top of the tower would have felt like cheating!). I pointed my nose straight up, and used 6 Skyward Ascents in a row, milking the full Thrill effect from each. Then I went into a shallow dive, and glided at a full 929% speed all the way. No sine wave. One vertical line. That’s how you Dragonride.