Sign up for Namebio.com reports.
Read everything you can find from the last 2 years. News, blogs, forums etc.
Study the top auction sites, What is listed in the top 100 And What has sold top 100
Avoid- Hyphens, mis-spellings, domains with more than 10 characters including the extension, number/letter mixes.
There are exceptions in the "Avoid". They are just niche areas that require more effort not suitable for a newbie.
Before you buy: Would you develop the domain? Check for all possible TM conflicts. Check search results.
Cost considerations : Reg fee/Auction price + commissions/fees + your time + % profit you want.
Is it worth your time based on comp sales?
Quality will always beat Quantity. You will need a lot of cash and time to play the quantity game.
So start simple. 10 quality domains or less. Plan on a 3+ year learning quest.
Go to NamesCon 2017 Las Vegas. Everyone you would want to meet will be there.
Happy Hunting !