I find irrigation systems difficult because of plant space and the need to move everything around each year; plus I do't plant in rows, but rather "blocks" as I have raised beds.
I hate using an oscillating sprinkler because of the amount of water than falls where there are no plants, but I do have a very sophisticated oscillating sprinkler (can adjust the width of the "throw" and also the outward facing angle of the jets (for narrower pattern).
http://www.gardena.com/opencms/opencms/UK/en/products/Product/index.html?html=true&prod=4078500197502#(Blurb says: Steplessly adjustable range: 7 m - max. 21 m. Adjustable width of spray: 4 m - max. 17 m. Mine is a different model that includes a timer. Horrifically expensive, but my local garden centre kindly honoured the incorrect price they had stuck on it
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)
Either way, best to have a timer so you don't forget you've left the water on. I have a simple clockwork one - but there are sophisticated ones that can do the watering to a schedule, unattended, even including several separate "zones schedules"
http://www.gardena.com/opencms/opencms/UK/en/products/Product/index.html?cat=PK410&scat=PK41005&prod=4078500119801&bls=0"
fully automatic control of up to 6 watering channels when used in conjunction with GARDENA Water Computer C 1060"
I have considered leaky/seep hose for rows (particularly hedges!), and I have used 1" or slightly larger "lay flat tubing" (the sort of thing that fluorescent tube lights are "wrapped" in) - comes in black too - and route it around the plants and then perforate with a pin a couple of times at each plant - better if it is perforated "underneath". (Don't get large diameter hoping to equalise the pressure, it takes more time to fill and doesn't seem to do that job, but if the pipe is long loping it back so you can introduce water from both ends, using a "Y" junction, helps IME)
That's poor-man's equivalent of a proper irrigation system with a main pipe and narrower bore distribution pipes with little drippers on the end.
e.g.
http://www.gardena.com/opencms/opencms/UK/en/products/Productlist/index.html?cat=PK410&scat=PK41010It is possible to put a "bung" in the holes of the main distribution pipe, if you change your mind about layout, but I wonder how practical they are for a changing vegetable garden (rather than a flower garden with plants in permanent places). That's definitely the ideal though as it gets the water to the plant.
I also have a friend how has put perforated drainage pipe underground along his raised beds. These would provide drainage, ordinarily, but his bath discharges into the system, providing water underground for his veg bed
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Other than that mulch to keep the moisture in. Cover the soil with organic matter (e.g. straw), or some sort of plastic membrane