Successful domaining requires a handful of skills...
1) Buying The Right Domains
Buying the right domains is the #1 thing you can do to increase your chances of success.
Where is the money? End user sales
Who are end users? Businesses with a product or service
Can you pick a portfolio of domains that an end user would want to increase your chances of a sale?
Ask yourself if I was in this business would I pay $500-1k minimum for this domain or could I find an alternate available for $10?
Turnover rate is low so if you have a portfolio of winners you'll be profitable if not you'll hear crickets as there will be no demand for your domains and the renewal monster will eat you.
2) Sales Landers
Do your domains lead to a clear simple sales page that makes it easy for an end user to understand the domain is for sale so they can submit their offer?
Do your sales landers load quick as slow loading landers could be closed before they fully load.
The average internet user is easily confused so simple works. Logos, graphics etc... may look nice on your site but they don't help sell domains. Domain quality is #1
Still parking domains? Make sure to use a parking company that has a big sales link located at the top of the page not buried at the bottom as a good domain sale can trump many years of parking earnings.
3) Distribution
List your domains on your own site, sedo, afternic etc... as good domains that nobody can find won't lead to sales.
4) Negotiations
Most of my sales since 2003 have come direct to my own sales landers which gives me name, ip, phone, email etc... to research who I'm dealing with and capitalize on sales without paying commission to an aftermarket.
Can you handle negotiations on your own through your own site, bodis sales pages, efty etc... or do you need to direct them to a better negotiator and pay a commission? If you do them on your own over time you will gain more confidence/experience as you talk to more end users.
So do I think you can make money starting today=Yes, but it requires a complete set of skills that some just get or can be taught and others continue to buy domains for many years later that have zero commercial appeal. If your domains don't appeal to end users than you will never see end user money. Good expired domains you can buy low, be patient and ring the register with an end user. Bad domains you can buy low, renew for years and eventually drop. Choose wisely.