1) Always under plant rather than over plant unless you need a terr that looks "instantly full" as you might for a wedding center piece or "get well" gift. Under proper conditions, a little terr like that will fill before you know it.

2) Always use less water than you think you will need. You can always add more if you really have to, but drying a terr out that has been overwatered (especially with a small mouthed container like that) before the mistake kills the plants can be virtually impossible.

3) Even though a micro Sin. like tend to like it quite humid, I'd recommend removing the plastic wrap. Moist stagnant air is often conducive to mold/fungal growth. Leaving the wrap off will allow for some air exchange but should still retain humidity quite well. Also, should the container get too warm, leaving the wrap off will allow the heat to escape rather than quickly building to lethal levels.

4) Place the vase where it will receive bright indirect light. If the terr is for a windowless desk area/cubicle, you will need to provide supplementary lighting near the vase. Overhead office lighting will not be sufficient.

5) Avoid fertilizing. With fresh media fertilizer should be unnecessary and the use of fertilizers is likely to result in lethal build up of mineral salts.

6) Do NOT water with tap water. Use RO water, rain water, or distilled water to avoid lethal build up of mineral salts.

Forgot to add:

6) Check out the FAQ for this forum if you haven't already done so.

Oh, and thrift stores like Goodwill/Salvation Army and garage sales can also be good container sources.

All good points. I can't leave the plastic off the opening due to the regular presence of fungus gnats. I'll be starting periodic treatment of the non-terrarium plants with tobacco tea. For now, I ventilate on a regular basis 'by hand'. I'm still looking for more micro plants to add, have s. muscicola for another planting. What plants would stay small and not become overly aggressive?

Update:

I have used resurrection fern on bark sold on Etsy,lichens and mosses from local creek/woods,miniature begonias,mini af violets.....

Button fern is lovely,may need to trim back a bit....