There is no shortcut to expertise my friend. Read up on the fundamentals. Grasp those then move onto the nitty gritty details of campaign management - which are the deciding factor in a successful campaign.
To be recognised as an expert, you would firstly need to pass the AdWords exam. This isn't a necessity but it adds that level of trust from prospective clients... This is a two part exam, with the first compulsory covering the Fundamentals (pass mark 85%). The second is a specialist area of your choice which can be Advanced Search, Analysis or one other I think (pass mark 80%).
Here's the link: http://www.google.com/adwords/professionals/
There's lots of tutorials and lessons, so get cracking!
"In 1969 I gave up women and alcohol - it was the worst 20 minutes of my life." - George Best