It will be a hard process if your new. I recommend purchasing trainers when they drop. When hyped shoes come out, they have a scheduled drop date. This drop date should also have a time and a method to purchase the shoes. (This requires research). The shoes that drop are in limited supply and as a result sell out in very quick times. This means that once they are gone, they are classed as dead stock (not available to be bought through retail (official websites)). Some companies restock items but others have a limited stock which they release all at once without any being kept in reserve for restock. If you are quick enough you can “cop” the shoes and will get them. You can then resell the shoes for a higher amount due to the very high demand for them.
Things to consider:
Research which shoes will be in high demand and are the most hyped, these will resale for the most and give you the most profit.
Brands/makes that are popular, some include: Bape, Supreme, Palace, Louis Vuitton, Off-White, Gucci, Balenciaga, Adidas, Nike.
This process isn’t just done with trainers and can be done with clothing and accessories with similar effect.
In order to speed up the checkout process you can buy a hot which auto fills the details and automates the process for you, ensuring you get the item before they sellout.
Hope this helps.