First of all we need to understand that Internet search engines are software programs and as such are brilliant idiots.
They cannot "understand" meaning or intention - you have to talk to them the way you would to a dimwitted child.
The second thing we need to understand is that there are many, many, many millions of web pages on the internet. Any search you run using a single (English) word will probably yield tens of thousands of pages - and most of them will useless.
Here are the top techniques on how to find stuff faster and easier with Google:
Be verbose
The longer your search query, the better results you will get. Instead of searching for "cheese", search for "mature cheddar cheese".
Where you are looking for a specific name (consisting of two words) enclose them in quotes, so: "Cape Town" - this will eliminate all other towns close to a cape.
Loose the noise words: "a", "the", "he", "it", etc - they just dilute your query.
Be geographically specific
No sense in looking at garden service companies on the other side of the world, or booking a guest house in a town you are not visiting.
Consider if the service or product you are looking for is geographically specific and include that in your search. For instance, "self catering cape town" will yield better results than "self catering"
Also use google.co.za instead of google.com when searching for more relevant South African information.
Don't worry about capitals and punctuation
Most search engines ignore capitals and punctuation.
Exclude noise words or include alternatives
Let's say you want to find out about studies or discussions about nuclear reactors in cape town.
If you search for "nuclear reactor cape town", most of the hits will be about Koeberg.
If you are looking to information NOT related to Koeberg, you can exclude it like this "nuclear reactor cape town -koeberg": in other words add "-" and the noise word you want to exclude.
You can also include an alternate term, like so: nuclear reactor cape OR "pebble bed" will tell Google to include all pages with either of the two search terms. (Note "OR" must be in capitals else it will be ignored)
We can further refine the search by adding additional alternates like this: nuclear reactor cape OR "pebble bed" (study or review) to tell the engine we are interested in either studies or reviews.
Use wildcards to complete phrases
If you are searching for a phrase, but you can't remember exactly how it goes, you can use wildcards to get Google to complete it for you. For instance: "And suddenly the penny ????" What? Fell? Melted? Levitated?
Ask Google, so: "and suddenly the penny *" Note the quotes and the wildcard character "*".
Another example, google: Better the devil you know: try searching for: "better the devil you * than *"
Improved search any web site
On many big web sites it can be very difficult to find what you are looking for - because they either do not have a search function, or it sucks.
Easy solution: use Google to search the site.
For instance, lets say you want to search the Microsoft site for outlook errors - just slap this into Google: "outlook error" site:microsoft.com.
Only pages from the Microsoft site will be returned.
Use expert engines
If you are looking for news stories, don't use the general Google engine, use the one dedicated to news: news.google.com. If you are looking for pictures, use the picture search engine: images.google.com.
Use more than one page
Before you commit to the results returned, scan the first and second page of google results. Note sites or content that you do not want, or alternatives you do want.
Improve and repeat your search so that the entire first and second page returns relevant, quality results.
Now you can start looking at the sites...but...open each link in a new window or tab so that your original Google search stays open. That way you can keep on refining your search as you home in on that little nugget of information-gold. (Right click on the link and select "open in new tab"
Synonym search
A problem one often faces when searching for technical information is that you may not know all the terminology / jargon. For instance if I search for nuclear ~reaction, I will get hits on "nuclear fission" too.
When in doubt and you need a little help, click the "Advanced search" link in Google for a page to help you build complex queries. (It won't help you find the floating GPS though)
Happy mining!