@ Bella....got to https://www.optoutprescreen.com and go to the bottom of the page and click the prompt. The next page click opt out for 5 years and you're done!! I just did it...if it works I'll share the news but not the buzz I get from the bump fixxxxxxx......oh yeahhhhh!
Starting Score: 
Soft pulls do not affect your credit and are not factored into FICO scoring models, only hard pulls. This is well documented so to say otherwise is incorrect. True - this is simply interweb-hype and any score increases would most likely be attributed to positive account aging, etc etc. As a previous poster mentioned, I too personally prefer to be opted-out as it prevents views of your CR by unknowns. Of course, this also means "pre-approved" offers, etc will be turned off as well because ... well ... this is how they "pre-approve" you.
If you are not opted out and app for a mortgage this allows JDBs and the like to also see you have been app'ing. This basically reads to them: "hey, this chap has some money to spend and since I have this old debt from 1882 I now have their current info and am going to go after them - here, let me add this to your CR or at least begin making phone calls to your OnStar number - and I'll send a few letters too!". Then, in the middle of the mortgage app process you now have a baddie on your CR. No bueno. This of course is my understanding from my research here in the FICO forrest and even from my banker. A mod or uber-experienced member could verify.
Too, Google it a bit more and you'll find page after page of credit professionals debunking the claim. Also, if soft-pulls affected credit then considering how often most of us do a looksie at our own reports we would all have 850 scores. Of course it would be a NEGATIVE 850 lol 