When I started out I made the mistake of prioritizing smaller items like cool-guy camo, the hottest new knife, bino harness, etc and thought I would be just fine going cheap on optics and boots. Fast forward to now having spent thousands and thousands of dollars and countless re-sells of gear, I will tell you if I could start over I'd have hunted in jeans and a flannel with a Jansport backpack if it saved me enough money to buy:
A. Quality optics. I'm not necessarily sold on some of the $3k+ options but a $1,000 pair of binos and a good tripod will absolutely increase your effectiveness.
B. Boots that fit your feet and work for you UNDER LOAD and AT INCLINE! You could have top of the line everything else but if your boots wreck your feet, it's over. I don't care how well you can tough it out. For me this meant lots of trial and error and purchasing 5-6 pairs at a time and returning the ones that didn't work. Don't always assume the most expensive or most heavily marketed boot will be superior. Last year I bought 5 pairs of top-name boots and threw in a pair of Zamberlain Guide Lux's because they were on sale for $200... guess which ones worked best for me...The cheapest option.