Unfortunately, to a large extent, it's going to be something you have to intuit from knowing your party. Is it a big group of unoptimized, heavy RP players? Easier/simpler encounters. A group of min-maxers? Go nuts.
There really is no good way to perfectly balance encounters without taking into account the characters you're throwing them at.
Early on, I'd just rely on the exp budget method until you get the hang of figuring it out. Most encounters designed with the exp budget should be fine, if a bit easy a lot of times.