Nice first work!
Enthusiasm gives the power to use just hand tools, but if you are really interested in continuing I suggest you at least a drill otherwise you'll get bored from the hard work.
You'll learn lot of things by yourself going on. My only suggestion now, that you can already apply with your tools, is to insist with grits.
I didn't know they can go till 12000, as Carver states, I use till 2500. Anyway, what I learned later than I would is that you have to sand and sand and sand before changing grit. From 120 up I keep on sanding with the same number till I take away the "mist" concealing the briar's beauty. Sometimes it looks like I already sanded enough, but untill I don't clear away that mist I don't change grit.