Time-sucks 2 and 3
2. Looking for the silver bullet
Most of the time, it takes dedication to a mix of activities to be successful in any marketing efforts. Rarely is there a silver bullet (although, some have been pretty lucky).
Even though marketers can't usually bank on a single tactic to drive their businesses, some continually try. The most common ones I see are companies turning to affiliate programs for "insta-sales." It is just not that easy. Decide on a marketing mix that meets your budget but also has room for experimentation to enhance that mix into the future.
3. Doing too many things (therefore, unsuccessfully)
Prioritize, prioritize, prioritize. Granted, I just said that the silver bullet just doesn't exist, and you need a marketing mix. However, it doesn't mean that you can't focus on a few things at a time. Prioritize tactics in terms of complexity and impact. Then, when you have your list, tackle each line item one at a time (while still keeping the big picture in mind). This process will ensure you maintain the optimal cycle of research, planning, follow through, and measurement.
This process will help keep you on-time and on-budget so you can continually make adjustments to task lists as the competitive landscape changes for your clients. If you are doing too many things when a major competitive shift takes place, it could displace too many projects and, therefore, critically damage a breadth of budgets midstream.