This is such a CRITICAL and GIGANTIC subject that it probably deserves an entire web site, purely devoted to it - methodologies, tactics, strategies, tools...
Here are my four essential components of a state-of-the-art followup system:
1. The CRM (Customer Relations Management) System
Every business that gives a rodentia's behind about their customer base has one. Do you? If not, why not? Too costly? Don't know how to deploy one?
The CRM is the nerve center of your business. It's where you "house" every last STITCH of detail about your suspects, prospects, and current business partners. If you are not in and out of your CRM tool suite on a daily (even hourly) basis as you work your business, then you are making a huge mistake.
Automation - wherever the technology presents itself, AUTOMATE the data gathering. Lead capture pages are a great first pass - often yielding only first name and email. Then the REAL CRM data-gathering stages begin: phone number, physical address, SMM PAGE ADDRESSES (these can be a GOLDMINE - especially here on Facebook), and the usual "lead survey" information that allows you to automatically sort OUT those you don't have time or patience to work with.
2. The Telephone
3 "types" of what is often referred as "touches" in the biz:
a. the Webinar invite call
b. the "after-the-webinar" info-gathering call (and in some cases, the close)
c. the follow-up call or MULTIPLE follow-up calls (these are the easiest ones to blow the sale - think FLIRTING and BEING A FRIEND, not wearing your recruiting hat)
3. The professional AutoResponder series
This component is often where the game is won or lost. Considerations such as how good is the content? What sort of gifts or giveaways (if any) are you sending? Is your BRAND and/or REPUTATION improving in their eyes throughout the series or are they just getting annoyed by you? Timing of messages is critical. There is no one perfect way - as in most marketing test-test-test and tweak, refine, and then test again.
4. ESM - the sneaky little secret weapon of a Master at followup - short for "Electronic Snail Mail" - huh? wha? this is where you click the mouse and off goes your followup campaign in the US MAIL (even foreign mail) - timed, just like your Autoresponder series, personalized, custom, including uploaded graphics and pictures if appropriate - SILLY amounts of followup power
The trick is integrating the 4, and then becoming an expert at using them effectively. Master this part of the biz and almost ALL THE REST GETS WAY WAY easier...