for me... ((no order to below just as i think of it))
#1 keep stuff out of the mud / grass.
other words rock / gravel, to concrete or like.
--use chunks of 4x4's and/or 6x6 lumber. to use as pallets errr something to place implements on to keep them off of the ground (from mud/grass from rock itself) primarily keeping metal from contact with the ground at same time keep implement from sinking into the ground. actual pallets stink.
#2 nice level flat area.
both tractor and implements need to be level when hooking up. so no hills or dips or like around. or trying to backup on some hill and hoping tractor will not roll in some direction while hooking stuff up to them.
#3 wash stuff off of mud / dirt / grass / weeds etc.. before storage. ALSO grease stuff up example all joints / bearing locations. and like. to help keep water from getting into these areas.
#4 finishing mower decks, rotary cutters. most of these mowers have some place were water could collect on them. set them up with a log or something under them so water will run off of them without need for a tarp or like over them.
--general duty buckets for FELs to backhoes, place them upside down or something so water does not collect within bucket itself.
#5 PHD (post hole diggers), rear blades, buckets, discs, harrows, plows, finishing mowers, rotory cutters, and much more are pretty much PURE metal. exception for some caster wheels / gauge wheels, and a belt here or there. these items will be find outside in the UV rays of the sun. if at most put shields back over the belts.
#6 sprayers, backhoes, (more so tractors themselves), see if you can place them in the shed. lots of rubber / plastic on them... that long term UV rays of sun will cause damage to.
#7 i dis-like tarps. way to easy for them to be torn up. all it takes is one sharp corner and the tarp will rip into pieces in one good wind of a day. also once you get tarps so snugged up and weight down they will not move. they can hold moisture inside them. and can become breeding ground for mice and like under the tarps. leave tarps to something else.... and use say a "lean to" or car port, were there is a ceiling over it all. does not need sides. just having a high roof over it. to block majority of the sun. and more importantly allow air to flow through everything.
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#8 lots of things have been kept outside for years upon years and are in still good shape. just keep the stuff cleaned up, keep it grease and take care of it. many tractors stay outside as well. do not get so caught up in trying to protect the stuff. vs making sure you can keep stuff cleaned up and in working order and easier to hook up and use.