Initiate Recruitment for Ministry
With few exceptions, people need to be recruited personally for ministry in the congregation, not pointed to a "signup sheet" or invited vaguely to "see Bob after worship." This is especially true if your goal is to broaden participation beyond a small group of regulars.
Personal means personal
Best recruitment is done by a personal telephone call, a face-to-face meeting, a personal letter, or a personal e-mail (not a broadcast e-mail).
Such methods require more work, and they require exposure to the risks associated with personal interaction, including the risk of rejection. Moreover, asking someone to serve requires the asker to understand why and for what and to hone the invitation. It is easier and safer not to take those risks. However, anything less than personal, while safe, probably won't be effective.
Present a planned, targeted opportunity
It is time to move beyond the "warm body" approach -- "Anyone who wants..." -- because it dishonors both the ministry and the audience. Instead, best practice is to think through the work to be done, to consider who in the congregation is well suited to do it, to make sure the same few capable people aren't being overloaded, and to approach targeted individuals.
Most ministries require at least some training. Some require substantial training. Best practice is to anticipate the need for training and not to assume that informally transmitted lore will be sufficient. Recruitment for ministry is an important opportunity to strengthen performance by signaling value and by equipping the minister.
Ask regularly, as needs and situations change
This is where a database can be useful. People often need to decline an opportunity to serve, but the nuance of their declining needs to be noted. It could range from,"not this time, but please ask me again," to "I'm not the least interested in taking on any ministry."
If one ministry wasn't suitable -- too time-consuming, too complex, schedule conflict -- another ministry might be welcome. Also, situations change, and a time-stressed member might have more time after job loss or retirement.