My Lone Wolf locks down rock solid with similar advice as has been given... I make sure to cinch up the top strap as tight as possible, flat and level to the stand, with the platform folded up. Then, I pull down on the vertical frame and lower the platform. Next, I install the second lower strap and pull snug but don't over do it. I then climb aboard and secure safety harness... With seat up, I put my left foot at the inner portion of the stand tight to the vertical frame, give the tree a bear hug, and use my right foot to lift up on the platform, while I put all my weight with the left foot and "set" the stand. Now the stand is rock solid, even if the tree is not straight... After the stand is "set" and platform is lowered, I usually get off and lift the platform a bit, and cinch the lower strap even tighter, then step on it for the last time... If you overtighten the lower strap, there will be "spring" in the platform, cables that are not taught, which I don't prefer... You'll get the hang of it and your preference. Depending on if you're "hanging & hunting" or leaving the stand up for awhile will determine how finicking you become... That first "set" with one/top strap will make your stand rock solid, the bottom strap is just added insurance... Great stands, and to me, perfect combination with the Lone Wolf sticks strapped to them. Typical sets work well with 3 sticks, occasionally (4) provide additional flexibility... Hope this explained it well enough. Happy to chat if it would help...
Side note: If the strap is "slipping", you absolutely need a new strap/buckle, period...! Should never slip, not to be trusted if it does...