Set a Budget, Then a Plan

Don't create a marketing plan, and then set a budget around it that you can't financially support and will need to change. Set a budget of what you can or are willing to spend on marketing, then write the plan to the budget. Remember to be flexible. You will need to adapt as circumstances arise, so don't lock up all of your cash flow on a predetermined plan. Stick with what works, adjust what doesn't, and try new things.