Things to watch out for -
where is the WINTER SUN going to be? 6 hours of sunlight per day is a good guide for healthy veg gardens in winter, though many of the tougher leaf varieties of plants can still do well (parsley, mustard, nettles). Main problem is it sets you back a little (depending on your climate) with potentially cold soils in spring.
LARGE TREES - (especially things with allelopathic tendencies like Eucalyptus and Walnut) Not only can they shade they shade your site on the wrong sides (such as morning sun), they often can and will send
roots to whatever vegetable garden you may be preparing. I have a large casuarina nearby that tends to suck all the moisture and nutrient out of the vegetable beds I initially prepared. What this means is that I generally have to double dig the area on at least a biennial basis. I would rather practice no dig, sheet muching, but have found that this is just not doable for the site that I have.
JOURNAL - buy a journal that you can carry around with you to note down ideas as they occur and make observations as your garden progresses. Its also a good place to put the information about what you have planted and where.
SEED SAVERS - try to find a local seed saving group or other people that are growing veg in your area. They can often give you a great start, as well as vital information about your climate and what does well in your area.
Other things to consider - prevailing strong winds and the potential for some sort of wind break plants; soil testing (at least for PH values); on site sources of mulch; and look out for local fruit trees that you can see are doing well. Peaches for instance are often better to propagate from seed from a local tree that is doing well. Loquats are also a great choice for an early fruiting species that is easily grown from seed.
Hope some of this helps.