This is just a brief and by no means comprehensive guide to getting better sweetcorn yields. Personally I find it an easy and rewarding crop to grow, but I intend to tell you the two things that increased my yields for those of you who are new to growing it or have had disappointing results.
First though a recommendation. Read and read lots when doing a vegetable garden. Magazines, books even the internet are useful, but don't fret if you're not an avid reader, many veg's are dead easy. You want to make sure your soil is right. I've no idea what type mine was, I just know they grew (google this info and choose a reputable site, not Joe Bloggs vage guide to growing stuff).
Sweet corn isn't the easiest thing to grow, but it is by no means difficult providing you follow the simple seed packets instructions more or less.
The two things that got me better yields though are as follows.
1) Planting in blocks, not thin rows. Why? This is purely to help with pollination. Sweetcorn is wind pollinated (so it'll be safe if all the bees die out as is being predicted if we don't do something soon) a thin line will allow the wind to whistle through and carry off the pollen to god knows where. A nice thick block will help slow down the wind and allow pollen to fall onto the waiting female parts (except during a tornado or hurricane). Gently tapping the mature flower heads in calm weather will also help.
2) Watering. During dry weather don't be tempted to drown the plants daily, instead give them a good soak every third day and follow the manufacturers feeding recommendations relatively closely.
Wait for the fillaments at the end of the swelled cob to turn brown and dry up then gently peel back some of the green outer husk to reveal a few developed kernals that are the correct colour for your cultivar/type. Push a fingernail into one and if a milky substance oozes out it's ready.
To pick, hold the plant stem with one hand and grasp the whole cob with the other and bend it straight down until it snaps. Eat immediately for the best cullinary experience, before the sugars begin turning to starches.
Don't leave them on the plant too long either or they'll not be worth eating. If you are someone who won't get through them quickly there are varieties available that will hold well on the plant for longer, just search the best seed catalogues, they usually have one or two.
I have not tried freezing or drying them myself so you might want to google that and get the information from someone who has done it or is an expert on it.
Only buy seed from sellers providing branded seeds eg: Suttons, Thompson & Morgan, Real Seeds etc. Make sure you ask if it is not specified in the listing. Those grown in someones back yard may be cross pollinated, diseased or from an F1 Hybrid plant whose seed won't come true.
I hope this helps.