Use escrow services for direct sales. When you are dealing directly with the buyer, make sure that any money that is transferred goes through an escrow service. This will ensure that all checks clear and that you aren't left with a bounced check and no domain. Escrow services may add a few days to a sale and cost you a percentage, but they can save you a lot of heartache.
Current Craze: When PokémonGo was HUGE last year, my domain flipping friends (Matt of Handshakin.com is one) were all about buying domains like PokeStopNearMe(.com) and other related domains associated with the PokémonGo craziness. It’s like the day trading of the domain world. You’re buying domains during the hype and hope to sell them for a higher price quickly before the hype fades.
If you’re patient enough, you can discover at least four to five very good .COM domain names at attractive prices. However, you’ll need to carry out some research and find out the right places where they may be available. I’ve seen that such .COM deals can also be bagged from popular domain marketplaces like Flippa.com, or from the private portfolio portals of sellers, provided you employ the right strategies. You can contact the domain owners directly too. There’s no harm in emailing them directly to negotiate the prices.
That said, my recommended budget for beginners would be $500+. Using this budget you could buy a bunch of high-potential $10 domain names, expired/dropped domain names or a mix of both. It’s very important to invest only what you can afford to lose and treat this as a side hustle till you get the momentum going. As you gain experience, industry expertise and some sales under your belt, you can then consider slowly growing your business into a full-time gig.