Generally, in order to lose a domain through a CDRP dispute you need to prove the following :
1. Domain is identical or confusingly similar to a common or trademark.
2. Registrant has no legitimate interest in the domain
3. Registrant registered the domain in bad faith
And note that the complainant would have to prove _all_three_ of those to win a CDRP.
The best thing is to read and understand the policy very carefully:
Sections 3 and 4 especially.
Important points are:
Date of your registration vs date of the mark. Who established rights earliest? You can't be accused of a bad faith registration if the domain was registered prior to any established use of the mark (unless you then blatantly infringe on the complainants mark after the fact).
Strong vs Weak marks.
If it is a strong trademark, as in something completely made up and "fanciful" then it is much harder for you to prove a legitimate interest, I'm thinking of things like CocaCola or Pepsi. Understanding trademarks is useful: https://www.uspto.gov/trademarks/basics/strong-trademarks
If it is a trademark that started off weak, but grew to be globally known and synonymous with that term, like McDonalds, you're also going to have trouble proving legitimate interest.
Put up an infringing ad and you're screwed because willful infringement equates to Bad Faith. Also, never contact a trademark holder to offer it for sale, that is considered Bad Faith as well.
Reselling generic domains has been quoted as a legitimate interest in several UDRP and CDRP decisions now. I wouldn't be afraid to claim my legitimate interest in a domain as an investment for resale.
Even fanciful/made-up domains have become investment quality in recent years, I'm talking about things like where you take a word and change the spelling (lyft vs lift) or you look for 4 letters that are pronounceable, etc... The key here is to never infringe, and show a pattern of investment in similar domains. If you own hundreds of similar domains you can show by the pattern of investing that it was legitimate interest (for your domain resale business) and that it wasn't bad faith because you didn't target a specific business.
So if you follow those key points, it really leaves the vast majority of domains open for investment.