Welcome! Hope you enjoy the site.
As for your questions, a great starting place would be to check out the site PinPics, a large database where you can find out all about pin sets, add your Owns / Trades, and figure out your Wants. Once you register there, you can add your PinPics ID to your profile here so the members can see if they have any matches with you for potential trades.
Strategy really varies from person to person. Have a look around the forum, and you'll start learning all about how different traders value pins (eBay price, PinPics Wants:Trades ratio, etc.), how to avoid buying scrappers, and much more. I hope that helps!