i wouldn't bother with soil unless you are willing to invest the time and research required to mineralize the soil (MTS route); basically convert the soil into a stable submergable state.
its an outstanding substrate if its done properly but its not conducive to frequent rescapes as every move results in (turbidity) cloudy water. it also runs out of juice (nutrients) after a year or so and breaks down into a compacted clay which is a pita to clean if you ever breakdown the tank.
a super lazy low tech way to convert soil would be to keep it submerged in a tub for four months (which i actually keep in my basement lol)
i would rather recycle the substrate you have as its somewhat already established and add or cap that. you can always add substrate ferts to keep root feeders happy for probabbly 10-12 months.
i did that with my nano; recycled my fluval stratum and capped with pfs i had laying around. so far so good and sorry for the crappy pic.
i think if you are just starting out, i recommend catching the collectoritis bug, and cram every living plant you can think of in there! join every RAOK thread, visit every LFS, creep, stalk tank journals, buy evey plant that interest you and ask all the questions you want in your thread! the important thing is you'll learn what works for you, types of plants you are atuned to, the style of scape that fits your taste... so plant plant plant...no fear! wooohooo!
I just used miracle gro organic potting mix soaked for a week in a tub with daily water changes. To avoid most problems just heavily plant the tank from the start. Many people have had success with it right out of the bag.