Grapes like their soil lighter and more gravely than clayey. However, we have the soil we have. Avoid wet areas.
The plants you get have a root system that has been pruned a bit, on average to about 8-10 inches. The hole does not need to be much larger. The greater area around it (ideally 4 foot wide) will be absolutely free of grass and weeds. To the backfill pile add a small amount of fertilizer (ie 8-12 ounces) and a quart of compost. The key here is to avoid babying the plant in that hole. The hole will wind up being around 18 inches in diameter and the material going back in will be mostly what came out of it. Set the plant do it is buried about 2 inches above where the roots appear. Fill, tamp down, then water (5 gallons), let settle an hour or more and then pack down again, adding more soil if necessary. It should be level. In that surrounding de-sodded area add more fertilizer and compost. For example, for one plant I like to add about 10 pounds of fertilizer (I normally use an organic 5-3-4 blend, but and general use fertilizer will work). Mix into the soil, then add mulch.
Now, for grapes you will not use the same amount of organic material for mulching. We will add a mixture of hay, hardwood chips, leaves, etc., but then like to topdress with stone in the area close to the vine planting hole. When we lay out a vineyard line, there is a strip of peastone, flagstone, etc. near the vines in a row so that the sun will heat up the area. This can be very important near harvest when it will release the heat at night to avoid frost and to build the sugar content of the berries. Having too much organic debris around grapes usually leads to trouble, and keeps the soil too cool in my opinion. You need to add organic matter and fertilizer each season, so further out you leave as woody mulch etc. while keeping stone closer to the plants. Grape roots will extend at least 8 feet into the soil and outward often well beyond this, so feeding the outlying area makes sense.
For simple pruning and training I like to use the 4 cordon system. Some folks like the simplification of 2 cordon, but you get less fruit. At planting, cut back to 1-3 buds. As the plant develops during the next few years you want to wind up with multiple canes. Ultimately you will have, each spring after pruning: 4 cordons (arms)- 2 on each side, and 4 renewal spurs (little stubs of a bud or two). This will be the case forever. The cordons should be a good 8-12 buds long for most varieties (some wine grapes can be cut to a spur system). Each year the 4 cordons will produce a crop along with the growth of new cordons from those renewal spurs. The next winter you will cut the cordons that cropped back to renewal spurs (you cut all off but a bud or two), and those 2 renewal spurs from this year will be producing next years crop. And so it goes, simple and logical. For those who are making arbors, the growth will be allowed to progress further, or more cordons are allowed, but they should all be periodically renewed from the base section of the vine to keep it healthy.
During the season, if the grape set is large, it is wise to thin out some of the crop or it may not all ripen. Some vines average about 40 pounds for a system like this, but each year’s weather will determine how much it can carry. Better to have 4 nicely ripened bunches than a bushel of sour marbles.
Grapes should always be set on a strong structure of some sort. The simplest is a series of posts with heavy wire (12 gauge minimum, airline cable about the best). There are rachet-type links you can insert to periodically tighten the wire without a hassle. Deadmen on your posts are a good idea (a diagonal line is attached to this buried rod or stone). A simple wooden or metal fence works fine too.
Grape setting distance depends on the vigor of the variety. An average distance is 8 foot o.c. in the row. For vigorous varieties like Kay Gray, King of the North, and Beta, I advise increasing this distance to 12 feet. If you are trying to grow more varieties, and in a limited space, reduce the system to a 2 cordon system and let the neighboring vine share the space between (ie the top space for a King, and the bottom for the Kay, that sort of thing). A grape can also be allowed to run wild and still produce decent crops. We have had single plants produce hundreds of pounds of grapes in a single season. There are records of a single plant covering over a quarter acre. Not advised, but impressive nonetheless.