Don't buy more than 10 or 20 in your first year and try and make a sale before getting to that amount.
Don't hand register names, look on expiring lists and email existing owners to try and find cheap bargains
Spend a lot of of time (months) reading this forum like you are currently doing and researching the type the name you are interested in, try and focus on something you are familiar with. we see new domainers registering Cloud, Robot or VR names but they are registering keywords not related to the niche at all and then wondering why they wont sell. Hand-registering VR or Cloud names is crazy, it was crazy doing that even 2 or 3 years ago because the good names were taken. Stay away from strange extensions, GTLD's or "hard to sell" extensions like .info, org etc
The most common mistake is new domainers going crazy and within 2 years they own 1500-2000 names and then renewal time come along. Most try and convince themselves that they are doing pretty well because they made a handful of xxx or x,xxx sales but the reality is they have lost a lot of money once you add up the domain registration and renewals costs.
Try and buy 3 or 4 good names and then try selling them. Always put yourself in the end-users shoes, don't buy names because you like them or think they have potential, especially when new to the industry. Make sure you research potential buyers before buying any names, it doesn't help buying a name "you" like and then realising you cant find anyone to buy it.
Good luck
