Try taking a break every so often which will lower your tolerance
if you smoke everyday your tolerance builds up fast
while on a break if you eat fatty foods and get an extra layer of fat over your current one where the THC molecules are stored this will help too
or just workout as much as possible without having a heart attack to burn off the THC soaked fat you will get closer to that first few times smoking high

i too find having a cig after a session gets me higher but i havnt seen any tests done and it may just be a lack of oxygen

hotboxing does work try making a fort like when you were a kid with chairs or a table and blanket or just use a car but its usually pointless unless your smoking a J or a blunt

also if you smoke one way for a while such as a bong then change to a new way of smoking i feel it gets me higher

also smoking a new strain will help