I guess it really depends on what you would consider a "freebie." I have found that to keep your list on the hook and pay attention, first offer part 1 of the freebie for signing up and tell them that you will give them part two in a couple of days, this way it's an ethical bribe to continue to open your emails.

Future emails themselves should contain great tips or advice allowing your viewers to absorb the information inside the email itself. In other words you are "training" your list to read the emails and a small portion of the emails (about 20-30%) will have a valuable download. This teaches them to 1.) open you emails. 2.) Read your emails 3.) click on any links in your emails.

I have lists that are quite responsive as much as a 30-40% open rate, consistently and 9 out of 10 times a 95% click through rate just using this method.
But remember to always, always give great content. One crappy email can kill it.

Cheers! 8)