Affiliate Marketing Secrets

this little question noone has been able to CLEARLY answer. I am creating a blog where I take pics from different clothing sites and post them together for ppl to “get the look”. I have also looked into store affiliate programs, not sure if i wanna do that just yet.
my question is, How can i have these pictures posted where I dont get in legal trouble? Do I have to contact each site individually and ask permission to use each and every pic? Fashion for the most part is time sensitive information so I dont wanna have to wait until something is no longer in season before I get permission to use a pic because I am not in a location where I can go to more stores or fashion shows.
I would appreciate if someone gave me a straight answer or send me somewhere that I can get answers to help me.