I usually make a batch and leave them a day or two in a closed sock drawer (or whatever you have that is similar) anywhere not hot and out of sunlight. After two days, I uncap and squeeze the air out, recap, shake, and put them back for two days.
I use simple flavors but find this works.
Steeping is not an exact science, most of the work is done for you by waiting. Just keep it out of sunlight, the rest kinda works itself out (my experience anyway)