A few weeks ago I made a post about this. I reached 15 in SP and I finally 'paid off my debt' to steem. Now I'm over 400 followers and I'm posting almost daily to keep growing.
My next milestone is to reach 100 SP and to have more than 500 real followers. Many followers are bots and people that become inactive quickly, so I think they don't really count.
I want also want to create around three good posts every week and be rewarded at least 15 SBD for each post.
Another big milestone for me is to be on the top of @steempunknet and @steemnova. Both games are in development and are not paying much yet, but I think that in a couple of months they will be giving huge payouts. Right now I'm level 7 on SteemPunkNet and in position 93 out of 375 on SteemNova.
Ahh also a big milestone that I recently achieved is reaching 50 points in reputation. That felt good.
I think that you are going about it the right way anyway. For those of us who cant buy thousands of steem we will have to put in the hard graft to be successful.
You have clear goals set out, comment and interact with your followers and post regularly. On top of that you are involved at the start of two exciting projects on steem. At this rate i think you will be aiming for a thousand sp by the end of the summer at least. 500sp takes the most effort to reach after that it really speeds up.
Thank you for your kind words! I will keep working hard to achieve those goals.