Choose method
Use multiples for comparable and stable businesses, DCF when you can model cash, sum of parts for different segments and asset value when these dominate. Contrast two methods without mechanically averaging them.
Build scenarios
Each scenario must combine internally consistent assumptions. Don't use optimistic sales with adverse margin unless you explain that relationship. Includes future equity, debt and cash.
Example
Central: sales +8%, margin 18%, 20x EPS. Adverse: 0%, 13%, 14x. Favorable: +13%, 21%, 24x. The range reveals what needs to happen.
Horizon and return
State a target date and calculate annualised return, not only upside. A 30% gain over four years is roughly 6.8% a year before dividends, very different from 30% in one year.
Update without chasing price
Review target when assumptions change, not to maintain an attractive upside. Save previous version and explain bridge: profit, multiple, debt or dilution. Separate consensus from your assessment.