I did this for 2 years before I got my climber…
First piece of advice - get a climber lol. It's not too late, they're readily available (used on FB or this forum if money is a limiting factor). I've seen 10x as many deer from a tree than I did on the ground.
Anyway, to answer your question. Comfort is key. Being at their eye level, you can't fidget. Whether that means a cushion on the ground or a chair up against a tree (what I did), you have to be comfortable or they'll see you before you see them. I would always set up against a tree wider than myself (both for comfort and to conceal silhouette). I would try to have some cover in front of me as well, but couldn't be blocking my ability to shoot. It's tough off the ground. People are far more successful than I was, but it is possible.