How to write a Sonnet

On the train today I was reading Writers Magazine, and noticed a competition to write a Shakespearean Sonnet. This interested me, as I am keen to try some new styles, and I was pleased to see that on page 57 they were going to tell me how to write one.....
.....boy did I feel stupid after reading that!

I suddenly felt inadequate as I didn't know what it meant to have 3 quatrains followed by a couplet, how to use iambic pentameter, with every line having the "familiar" five feet (ah yes, those familiar five feet...poems have feet??!!), that is it only ok to starting a sentence with a stressed syllable if you are placing an initial trochaic substitution  and that you can use the recognised variant of a a feminine ending......bla, bla, bla...

...my brain boggled.

However, I have actually quite enjoyed researching what seemed to be gobbledygook and now feel (slightly) ready to attempt a Shakespearean Sonnet. So if you are interested to give one a go for the first time, here is my understanding of how to write a sonnet and what it all means (with a lot of credit going to Wikipedia). 

Firstly, a sonnet is 14 lines consisting of 3 quatrains and finished with 1 rhyming couplet. 
A quatrain is a stanza (or verse) with four lines, where the 1st and 3rd line rhyme with each other, and the 2nd and 4th line rhyme with each other. To let the sonnet man himself explain, this is 1 quatrain: 

Let me not to the marriage of true minds
Admit impediments, love is not love
Which alters when it alteration finds
Or bends with the remover to remove

A couplet is a pair of lines that rhyme, as the famous sonnet finishes: 
If this be error and upon me proved,
I never writ, nor no man ever loved.

So you need three quatrains and 1 couplet at the end - easy right? Well, of course there's more.

Rhythm in poetry is measured in small groups of syllables; these small groups of syllables are called feet.  For example, a foot that is one unstressed syllable followed by a stressed one is an iamb. The spoken sound of heartbeat illustrates this well - "duh-DUM". When spoken, the first syllable is unstressed, the second syllable is stressed "da-DUM, da-Dum, da-Dum"

This is important to know because the pattern used in each line of a sonnet is iambic pentameter. Iambic because it uses the foot (or pair of syllables) just mentioned,  and pentameter because it has five of these feet per line (i.e. a total of 10 syllables). Wikipedia gives a great example from Keats: "To swell the gourd, and plump the hazel shells". 

If you say that out loud, you can hear the "da-DUM" of each foot. If I re-write it with the stressed syllables shown it helps "To SWELL the GOURD, and PLUMP the HAzel SHELLS"

Still with me? It takes a bit of getting used to. 

Every good story needs a twist, and this one is no exception. There are alternatives to the basic iambic pentameter that can be used in a sonnet.......

1. Troachaic substitution - This is where you switch one of the iambs in a line to become a trochee, which is just a foot that is the opposite of an iamb,i.e. a stressed syllable followed by an unstressed one. An example is "To BE or NOT to BE; THAT is the QUESTION". "THAT is" is a trochee, all the other feet are iambs. 

2. A Feminine ending - this means adding an extra unstressed syllable to the end of a line.

And, finally the topic can be whatever you want it to be, there are no restrictions. I have put some useful links below if you want to go into more detail.

Now all that remains is to write the thing........move over Shakespeare :)

Useful links: 
Metre in poetry: http://en.wikipedia.org/wiki/Meter_(poetry)
Iambic Pentameter: http://en.wikipedia.org/wiki/Iambic_pentameter
Trochaic substitution: http://en.wikipedia.org/wiki/Substitution_(poetry) 
Trochee: http://en.wikipedia.org/wiki/Substitution_(poetry)
Sonnet: http://en.wikipedia.org/wiki/Shakespearean_sonnet#English_.28Shakespearean.29_sonnet