Start with market research first for your type of products and services. Check with similar products, replacement ones, etc. Market prices are the most important. You should know your cost prices of course.
Make P&L calculation, checking with different quantities and leaving certain money for marketing. At the end you will have several options. This puzzle will help you to decide which one is the feasible, and go for it. Do not take unnecessary risk, but look for revenue always.
all the best
Val