Stick with the ladders for now and just be sensible.
Balance and confidence comes with repetative use. But beware of overconfidence. In the winter beware of slippery surfaces. This is mainly in sheltered North facing parts of the house where the sun never shines, so moss can be deadly. In winter rub your foot on any surface your unsure off. If it feels slippy dont go up your ladder, or if the customer wants the window cleaning get them to foot the ladder.
The ladder you use should have angled rungs so when you are stood on it your feet will be flat, it safer and more comftable for every day use then rungs that are square with the frame.
Wind can be a problem. My ladders have wooden sides with ally rungs, I find them more stable in windy conditions, I have worked in Gale force to storm force winds, not clever I know but I have a lot of experince with ladders.
Tip, If its very windy do all the top windows first and then lay your ladder on the ground, If you dont a sudden gust of wind could catch the ladder and blow it over causing injury or damage,.
Nel.