Keeping your boat(s) in mint condition will certainly serve you well in the long run. I like to tighten up all my bolts and screws. On Pyranhas, most of them can be done with a simple hex key. Another thing to do is to spray some WD40 or other water disperser/lubricant on your ratchet straps if you have them. This prevents them corroding and makes them run satisfyingly smoothly.
It is also a good idea to adjust and tune your outfitting to suit you. Even the subtlest raise in seat height or adjustment of the foam in your hip pads can make all the difference in your contact with the boat and the water.
This is a great outfitting tutorial by Bren Orton, and can be applied to most kayak brands:
You can buy outfitting foam and replacement parts from your kayak company:
Exo rope system: https://www.youtube.com/watch?v=EPq70NTbeoc
Strength and Fitness
Strength and endurance are key factors in your paddling ability. Strength and power are important for manoeuvring your boat, paddling fast and hitting moves. However, endurance and cardiovascular fitness are also vital for being able to maintain control and concentration throughout the duration of a rapid.
Arguably the best workout for kayaking is actually going kayaking, but if you are stuck at home here are some great exercises to try:
Russian twists: Sit down with your feet in the air and your back suspended off the ground and move your hands (you can use a weight) from side to side touching the ground. Do as many reps as possible. This is great as it simulates the side to side motion of paddling.
Other core exercises such as sit-ups, dish, and plank are great too.
Arms and shoulders:
Press-ups, shoulder press and bicep curls are great for arm and shoulder strength.
A great way to improve your kayaking is watching older videos of yourself paddling and analysing what you did wrong, did right, or could have done better on. You can keep this in the back of your mind and put it into practice later on. Being critical of yourself and looking for holes in your technique will really help you.