Remember, you can check the full document Paschale Solemnitatis on this site, among many on the internet. Sections 48 and 49 describe necessary preparations for Thursday’s Mass. Altar bread first:
48. The tabernacle should be completely empty before the celebration. (Cf. Roman Missal, Evening Mass of the Lord’s Supper, 1) Hosts for the Communion of the faithful should be consecrated during that celebration. (Sacrosanctum Concilium 55; Eucharisticum mysterium 31) A sufficient amount of bread should be consecrated to provide also for Communion on the following day.
Attendance for the first two days of Triduum is often stable. It can be useful to track numbers of worshipers, especially on Friday, recording this for the following year.
The place of reservation is essential. The predecessor of the CDWDS, the Congregation for the Sacred Rites, drew up the earlier document cited that predated Vatican II reforms.
49. For the reservation of the Blessed Sacrament, a place should be prepared and adorned in such a way as to be conducive to prayer and meditation; that sobriety appropriate to the liturgy of these days is enjoined, to the avoidance or suppression of all abuses. (SRC, Decr. Maxima redemptionis nostrae mysteria (16 Nov. 1955), n. 9, AAS 47 (1955) 805)
A separate chapel, if part of the church’s architecture, is appropriate.
When the tabernacle is located in a chapel separated from the central part of the church, it is appropriate to prepare there the place of repose and adoration.
Sometimes such chapels are too small. In my experiences, a church basement has worked, but good effort is put into making it suitable. Any good experiences to mention from you readers?
Catholic Sensibility 
Two potential problems with the use of a lower church/undercroft/basement:
1. It tends to make a hash of the procession.
2. If not handicap-accessible, you’re limiting access.
In the preconcililar ritual in the USA, the floral decoration of the place of reservation was often the most elaborate of the entire liturgical year. But it’s an a thing where cultures vary. A friend of mine who grew up in Bogota before World War II said the custom in her culture was that the place of reservation was spendidly decorated, not with flowers but with sheaves of wheat – both real and gilt-artificial.
We use the parish hall, which works well. My ingenious decorators have come up with a free-standing PVC pipe structure, easily assembled, from which to hang the backdrop to the Tabernacle of repose.