Tips for a perfect wash

I usually use cold water in my washing machine, I will do a hot water wash only on whites. I use homemade laundry powder (recipe here) and I always treat stains before I put them into the washing machine. I have a front-loading, five star washing machine. I’ve washed this way for years. I’ve never had a problem with dirty clothes, colours that fade too quickly or hygiene problems with underwear,