I see the same things among the people I teach kayaking again and again. Everyone is different and there are different ways to reach your goals, but drill a few things into your paddling and you'll be free to concentrate on that elusive next level.
There's a difference in kayaking style when you're in your comfort zone and when you set off down an intimidating rapid. When zoning into paddling a more difficult section of river I often notice a very tight grasp if not a white knuckle grip on the paddle shaft. A sort of fight response to an impending challenge. I would like to take a second to demonstrate how this is highly detrimental to your paddling style.
The white knuckle grip often also means that you become rigid with full body stiffness . From your hips to your upper body you should be loose in order to react better to turbulent waters. If you are tensed up when kayaking, waves and cross currents are far more likely to knock you over. You should always aim to be loose and relaxed.
My biggest peeve is the instruction to paddle from your 'toes to your hips'. I could be diplomatic and make a case that the last part of your paddle blade exits the water at your hip. But that maxim has just caused too many people to develop poor paddling form that it should be thrown out. New paddlers bringing their hands back in line with their hip makes them bring their paddle out far too late. Forward power turns into a turning stroke, and your core is allowed to relax, losing the connectivity between your upper body and lower body.
So instead, paddle from your 'toes to your knees'. If you realise you have to start taking the blade out at your knees then you'll realise you must reach further forward by winding up your torso in order to get a good powerful stroke in. Your hands remain in front of your body during the recovery phase as the paddle begins its exit from the water at the optimum point between your knee and your hip.
Reaching forward toward your toes and bow (and the 'catch' of your paddle in the water) is the key to getting the most power from your back and avoiding short strokes. Next time you paddle make sure to check if your hands always stay in front of your body when you forward paddle.
This is the magic stroke in kayaking. Day one of a beginner kayak course in moving current. It’s the stroke which unlocks the door to understanding core rotation. During a stern rudder you should be rotated enough so that if you were to let go of your paddle it would not hit any part of your boat. It makes breaking into and out of low-flow eddies a breeze and when it takes just a few strokes to ferry across the whole river you'll understand why its called ‘ferry gliding’ not ‘ferry paddling’. You can use the current to your advantage, moving water is not something to be fearful of. In addition, surfing your first small wave with a stern rudder is super fun and gets people hooked on the sport.
The stern rudder comes in handy all the time, for adjustments when sliding down big rocky slides or surfing enormous river waves.
Too many needless strokes! The timeless advice of 'Paddle like F*#k' stuck with me for years and at times still comes back to haunt me. If you paddle non-stop downstream things come at you way faster and you have so much less time to pick smooth lines. The best paddlers paddle some of the most difficult whitewater, most of the time taking barely any strokes. Racers at the Sickline paddle like crazy on the flat sections but then relax during the rapids just focusing on those three or four key strokes they need.
The number one problem I see when teaching people to boof is taking a flurry of strokes right before the boof stroke and so missing the all important key stroke. The PLF mentality supposes that you're more stable when at speed. Ask yourself if you're are more stable after you've paddled full steam into a rock because you were focusing solely on your stroke rate. Frantic paddling is bad, smooth paddling is good. Beginners typically flip over on eddy lines and against rocks, not in the centre of the flow. It's more effective to build some speed on the entry to generate the right momentum, then slow down and focus on taking the strokes that matter.
Lastly, don’t get into the habit of following another piece of plastic in front of you down the river. I always encourage even absolute beginners to lead down suitable rapids. Reading whitewater is just as important as learning to manoeuvre your boat. Yes, sometimes you'll choose the wrong lines but you will learn from it. It's far better that, than somebody who has been paddling for years but is still reliant on other paddlers to show the way. If you don’t feel confident leading down rapids, then recognise that and take a step back. Focus on leading down rapids which are a step or two below your ability, work the river and make harder moves for yourself on easier rapids, then as you get confident not following the leader, use the leapfrog leading technique to share the lead on something harder with a friend.