Instead of making spam threads telling everyone to add you, just put it in your signature.
http://www.steamprofile.com/ is a great site to find little signatures you can use to show your Steam status and games, as well as your avatar.
Put this in your signature by going to My account -> Edit signature and copying and pasting this code:
Code:
[url.=http://steamcommunity.com/id/greeksrule][img.]http://steamprofile.com/profile/extended/steam/greeksrule.png[/img][/url]
Remove the dot from [img.] and [url.=http://etc] is all you have to do.
All you have to do with that is be an active member on the forums and people can just click that and go to your profile and add you.