Written from a printed household puja book and not yet checked by a second reader. Follow your family's own practice where it differs.
What to gather
Everything the puja needs, as a checklist. Ticks are saved on this phone, so you can gather over a few days and pick up where you left off.
For the offerings
Food and prasad
Lamps and vessels
Cloth and setup
Making panchamrut
Half a bowl of milk, with one spoon each of curd, ghee, honey and sugar. Keep the five apart while the puja runs, because each is offered on its own during the bath, and mix them just before tirth is taken.
If curd, ghee or honey is not at hand, use half a bowl of milk with a spoon or two of sugar as the panchamrut.
If something is missing
Where a leaf or an item cannot be found, offer akshata in its place and say its mantra. The puja does not stop for a missing leaf.