I like to invest in new and upcoming projects at discounted prices before they release on the public market. How do I buy in these private sale rounds at cheap prices?
As far as I know, private sales are usually for ventures. It's not easy for individuals to win a private sale slot. You either need to join a well known ventures or follow the projects really close and fight with other thousand people to get a slot for individual investors.
Which is the most reputable best smart contract platform that has its own launchpad that introduces new upcoming projects? Which smart contract platform launchpad verifies and audits all upcoming/new projects and its code to check whether the project is a shit/scam coin?
There are a lot of launchpad platform, many of them are not guaranteed. You should stick with exchange's launchpads to avoid being scammed: Binance Launchpad, Huobi Prime or OK Jumpstart (of OKEx). After being sold, tokens are listed on selling exchange as a guarantee of profit.
So far the most reputable launchpad platform is Coinlist. They have a good procedure of evaluating projects and good relationship with big ventures. Most of their projects are listed on huge exchanges after sold with high ROIs.