A greenhouse works best when its size, position and base are decided before the boxes arrive.
Measure the site before picking a size
Start with the level ground you can actually use, not the whole yard. Mark the footprint you are considering with removable tape and walk around it. Leave room to open the door fully, to carry trays in and out, and to reach every side for cleaning. Check overhead clearance for branches and eaves. A smaller greenhouse that fits well usually serves better than a larger one that crowds paths or sits in shade.
Check light, wind and access
Watch how sun moves across the spot during the day, and remember the angle shifts with the seasons. Note how exposed the site is to strong wind, since an exposed position puts more strain on any structure. Being able to reach water easily makes daily care simpler. Conditions vary from yard to yard, so observe your own space rather than relying on general rules.
Plan the base and anchoring first
A greenhouse needs a level, stable and free-draining base. Decide on the base before assembly day, and follow the product's anchoring instructions exactly, since anchoring is what keeps the structure safe in wind. Prepare the ground before you build, and if you are unsure whether your soil or slope is suitable, ask a local professional before committing.
Read the product details before ordering
Check the listed dimensions against your taped-out footprint, including door width and overall height. Read the frame and panel materials, what fixings are included, and what is sold separately. Look at the assembly instructions and care guidance so you know what the build involves and what upkeep to expect. Do not judge capacity from a photograph alone.
Start with what you already grow
Begin with plants you already understand, and keep a simple record of what does well in your conditions. A local nursery can help match plant choices to your climate and the season. Once your routine is settled, expand gradually rather than filling every shelf in the first week. A greenhouse you can keep up with is more rewarding than one that gets ahead of you.
Image credit: Photo by Oksana Demenko (@_kseniademenko) on Unsplash, free to use under the Unsplash License. https://unsplash.com/photos/IjrhisHP7_k