Yes is the short answer. Any time you are planing on generating money, you should have a plan. No plan means no real focus. There may be some 1/1000 percent of a chance you will succeed, but I haven't met them yet. If you have already started and have generated an income, record how. Doing so will give you material for use in expanding your business faster.
It’s also important to research their payout structure. Not all payouts are the same and tier affiliate marketing often offer different payouts. Some might pay you on the first offer but pay you nothing on any upsells. Ideally, you should be paid for every transaction. In doing your research, you’ll find out which affiliate payout structures are the most profitable.