I generally use commercial products and spray my finishes. But, if you want a darn near foolproof finishing schedule with superb results using products you can get at any Big Box store... This is a pretty good way to go:
Sand all wood to 220 grit, then wipe on a coat (or two if you like) of Minwax Antique Oil. This "pops the grain" on most woods and adds depth to your final finish. It also acts as a sealer so your finish coats go on much smoother.
Next day wipe on a coat (or two) of Minwax Wipe-on-Poly. You could use this product to build a beautiful finish, but it takes at least 6 coats to really build to a nice protective layer. Sand off any raised grain or nubbies between the earlier coats.
You can use this to build a great finish much faster. Two or three coats brushed on undiluted or slightly thinned works well. The idea is to thin it enough you don't get any brush marks. It dries about three times faster than Helmsman Spar Varnish. You can also thin it with spirits 25 to 50% and make your own fast drying wipe-on varnish.
You don't really need to use Helmsman Spar varnish for your interior finishing. It drys pretty slow, so there is more chance of dust, bugs etc. getting in your finish; and it can take days to apply multiple coats and you don't generally need the UV protection it offers inside.
There are many other ways to finish wood. This is just one of the simpler methods I know of that will give you a furniture grade result... and anyone can do it. Just some kindly advise from and 'ol guy that has inhaled a lot of fumes over the years.
If you really want to learn about finishing... Get Michael Dresner's or Bob Flexner's book: Amazon