I have stopped and started collecting several times, and have used many different strategy. One way that is very good, but not the one I would pick you can see if you go to Youtoube and type in: Marvel Man how to start collecting(note: this is not me)
What I would do is go to a comic store, any one would do. Look at all the comics around you, pick one that looks cool or at random, read it and see if you enjoy it. If you do buy it and other issues of the same series. That is the foundation, now that you have done that it is pretty easy to continue. After getting about ten or even twenty issues of a series you like, go back to the comic store. Find a different series, preferably from a different compony, but hey "what ever floats you boat." Then buy ten or twenty of the new series, while still collecting the old one. Once you have four or five series going, find a common denominator. Are they the same compony, genera, writer, artist or even hero? Find that and you know what kind of comics you like. Maybe you like Frank Miller, or Horror, or DC? After this you will notice, that you have actually been collecting for some time. But now you can become a serious collector. Subscribe, make monthly trips to the comic store, go the www.mycomicshop.com. Don't worry about not having T-shirts or memorabilia, just worry about getting, reading, enjoying, and collecting the comic books. You might have some people tell you that you are not a comic fan, but "to Hell with them." If you like comics, but not the memorabilia, then you still are a comic fan in-fact you might be a better comic fan then most.
Online or in comic stores you might see signs saying, AUTOGRAPHED, or SPECIAL EDITION, ignore those, the stories are what's important.
[Helpful tip: Buy comic boxes so you don's lose all your comics.]