When you will be ranked to member or at least Junior member, you can try to enrol into sigmature campaign that you like, and then they might accept you
Now a days the most important thing for getting accepted in a campaign is the post quality... you might have a sr. member account but if your post quality is poor then it would be hard for you to get accepted in a good campaign.
actually, i have seen a lot of sig campainings, where spammers existed for a long time, and they are still feeling fine.
it is not a problem in most cases, if anyone knows english language pretty good, he won't have that problem right?
I don't know maybe if someone knowing english will not be counted as a spammer but i don't think that is how it works because mostly campaign managers see the quality of your posts but not your grammar...