Step Three takes as much time as Steps One and Two combined often. In this case it took just a few minutes to sand the flower box and then only a few minutes to apply the stain and shellac. What took time was allow the finishes to dry property. On large projects you can pour hours into sanding and finishing.
There are hundreds of books filled with information about preparing wood for finishing. I am going to pass along a few points that I have learned and adopted.
1. I always start with 60 grit sand paper. The material might appear to be ready for 120 grit right off but it probably isn't. I have reduced sanding time and use less fine grit paper by starting rougher than it first appears to require.
2 I have cabinet scrappers and hand planes, and still mostly use sand paper. It is what I learned on and know best. Doing what you know best is the most effective use of time.
3. Always sand with the grain, always.
4. When I work my way through the sanding process I use 60. 120, 220 and 400 grit on both hard and soft wood. I use a random orbital sander until 220 and then I switch to a finishing sander. Often the 400 grit is done by hand. I do mostly small projects so hand sanding is realistic.
5. Buy good quality sand paper, it does last longer and I think it does a better job.
6. Don't ignore a belt sander when doing larger projects, but be careful if you are using course grit paper.
7. When you are done sanding dampen the wood with water to raise the grain and sand some more.
Before you start putting on any finish rub you work down with a tack cloth or at least vacuum it.
If you are using a open grained wood like oak fill the pores if you want a great smooth finish. I usually put on a coat of shellac and sand it off leaving shellac in the pores of the wood although there are other fillers on the market. I learned with shellac and know it best.
It the case of this project I stained the wood with a water based wipe on stain, I let it set for a couple of minutes and then wiped off the excess. Next I gave it 24 hours to fully set and lightly sanded it. Even though I had raised the grain before there were a couple of spots that were slightly rough after I put the stain coat on.
I then put on a 1:2 ( shellac-alcohol) coat of shellac, sanded and followed with two coats of 1:1 shellac. I allowed several hours for each coat to dry since it has been humid here this past week. Between coats of shellac I use an abrasive pad to knock down any bumps formed by dust. Steel wool also works fine though I find it shreds if I am not careful.
There are hundreds of books teaching, explaining and talking about sanding. Like sharpening, find a system and products that work for you and stick to them. There is nothing worse that messing up a project in its final stages with a finish the wrong colour, or that won't dry or something equally nasty.
If this was a baking project finishing is the icing on the cake, or the presentation, size and shape of the cookies. Like a fine finish on a wood working project Stage Three will not change whether the project works, it will change how it looks and what other people think of your work.
It was a prep, assembly and finishing project. Making things takes attention to all three steps.