All the steps can be performed much quickly with Asinhunt
1) Choose a category
start by choosing a category you plan to focus on
2) Keyword search
then do a keyword search in the category for the type of products you think would sell well
3) Collect data from the keyword search results
your goal is to collect a list of about 100 products and some specific data:
4) Analyze and filter results
Eliminate the products from the list that have high number of sellers, low rating, low selling rank (anything above 50,000 ~100,000 in the root category)
5) Check sourcing price
Now with a much smaller list of potential candidates, search for suppliers and see what is the wholesale price. If the wholesale price is much lower than the "net revenue"(collected in step 3), then the product is a good candidate.
6) Calculate costs
Add your costs to the wholesale price. For each unit, calculate: shipping(from supplier to Amazon or to your house), packaging, customs, inspection(optional), advertising cost(optional), other fees such as payment processor, sales tax.
7) Start selling
Now it's up to you to decide how many different products you want to sell but better to start with only one in the beginning.