You can look at this as an FAQ most beginners have regarding vegetable gardening. The answers to these questions will decide the type of plants you should go for.
The most important question is "what to grow and how much?"
Before you start off you need to decide what vegetables to grow. There are several factors to be considered while making this decision. A few important ones are listed below
It won't be worth while growing vegetable you don't personally relish. It makes sense to make a small list of vegetables you and your family like to eat. It could potatoes, tomatoes, spinach, lettuce, celery or broccoli.
You could consider growing vegetable purely for the purpose of salad. In that case lettuce, celery, gourmet cucumbers and other greens would be in order.
You might also have a need to grow to a particularly ornamental vegetable or a variety which is not available in the local market.
Remember that most vegetables would need to be stored since you wont be able to finish the lot in a few days. You need decide how long you are planning to store it and how much would you like to grow. Might be a important question for you to answer as a part of planning a vegetable garden.
If you are a small family you would need consider growing a limited quality of vegetables, than if you are large family.
The feasibility aspect is a priority if you don't want to end up disappointed after planting the crops and reaping a poor harvest.
Some vegetable prefer a warm climate while some prefer it cold. Some can withstand extremely cold climates while some just wither away.
Some vegetables have faster maturity period than others and might work out in regions which have a quick summer and extended fall. Some vegetables require a long duration of cold or warm climate to mature properly.
These are some practical considerations before planting the vegetable garden.
Some vegetable require a large area to grow, while some can be planted with a small square footage.
The consideration should be to plant vegetables which can give a reasonable amount of produce in the space you have available.
For example pumpkins require a lot of space to grow, whereas carrots take much less space.
Some vegetable are very fussy and require a lot of care and attention. Several vegetables on the other hand are low maintenance and grow under average conditions.
You need to decide if a fussy vegetable is worth the time you would need to devote to its growth.
For example: Cauliflowers are high maintenance plants. Not only do they succumb to several pest infections, but then need to blanched properly for the vegetable to get the right color and flavor.
Some vegetables are cheap to buy from the outside and require a lot of effort to grow in your garden.
Corn is the best the examples. They are very cheap and can be purchased in good quality and cost from a market, but growing it requires a lot of space. Each plant would yield one ear of corn while taking a lot of space to do so.
Potatoes would be another example. They are cheaply available in plenty at any store but they require a lot of space to grow in the garden.
Whereas if you plant Asparagus you can get a good crop year after year, without having to pay heavily for buying fresh ones in a store.
Then again there is a consideration for freshness. People grow vegetables in their garden to get fresh produce. So if freshness is your only consideration, you can throw this aspect to wind.