If you're just dabbling then by all means play around and see what happens. The Google Keyword Research Tool is probably the best indicator of good keywords as it tells you traffic and cpc levels as well as suggesting synonyms based on your phrases.
However if you're going to be spending 1k - 1.5k a month initially (which has always worked for my clients) you'll want a professional looking after the account so it can be optimised. An adwords manager will usually charge up to around 22% of your adwords budget to manage it (although, shameless plug - we're a bit cheaper).
If you want to keep at it yourself here's a bit of advice:
Common practice nowadays for keyword research is to come up with your own list of generic keywords and a seed list. A seed list is a list of phrases you think potential customers will be searching for.
The seed list will likely be more accurate, whereas the generic list will initially cost you money, but if you combine it with google analytics you can learn quickly which phrases result in conversions.
E.g. you may choose the keyword 'ecommerce' if you are a web developer and by checking your analytics account you may find that the following phrases convert:
magento developer
magento development
whereas the following are never going to, and can therefore be excluded from your campaign and cost you less:
magento tutorials
magento hosting
magento sucks (just kidding, it's great

)
I hope that gives you some pointers. Feel free to get in touch if you have any questions, there's a lot more that can be done regarding match types etc.