Yesterday Ramlan-sensei came to Singapore to teach. He had two main points on our technique.
One was to always remember your line of power. The line of power is that line which starts at the tip of your finger in proper kamae and ends at the outside edge of your back foot. This line includes your wrist and elbow (both straight and flexed but relaxed) as well as your hips (weight slightly forward 60/40 distributed onto your front foot). This line of power should at all times project through uke and determine the direction of your movement. In essence, it can be thought of like the barrel of a gun.
When techniques are weak, it is often due to the fact that shite's (rather than uke's) line of power has been broken/disconnected. Many times this happens at the point of our elbows (when not tucked into our armpits) or at our hips (which come off the line). It is easy to see when Uke lags behind shite (they should always be in front - on the line). It is essential for strong technique to keep everything in line - the line of power.
Ultimately, this line of power is aimed at the uke's weak line. That is, our line aims at a point not of uke's strength (which would clash force on force), but at a point of uke's weakness. This makes strength less necessary for completion of a successful technique.
The automatic line of power can only be achieved through training in kihon dosa, the basic movements of Yoshinkan aikido. These must be done mindfully with intention to be centered on the line of power. Over time, this will become instinctive. Keep training.