Best way to slim down?

So I'm trying to go down 40 pounds. I started eating a LOT heathier and I've been going to the gym. I keep hearing different opinions. I hear to just do cardio and then I hear that I should do 35 minutes of cardio and then do machines. What was the best way you lost weight? My targets are my stomach and thighs. I had a baby too so my skin is a little loose. Any help would be lovely!