The higher your rank, the higher your chance to join the great project in here, such as bounty, campaign, or good airdrop. So what will you do is up to you. What makes you want to reach jr. member ? is it to join greater bounty, good campaign or the join the other good project. So it's all back to you again, to your motivation what makes you want reach jr. member.

When you reach the junior member, try to find a campaign which accept junior member with a good project and which don’t ask you a lot of effort like 7 posts by week (unless you're a big talker).

You will reach jr member when your activity = 30.
The activity number is  :
time = number of two-week periods in which you've posted since your registration
activity = min (time * 14, posts).

So, if you post one by day => you can get the maximum number of activity points.
It doesn’t mean that you must spam.
If you post more than one by day, the number of your activity will not increase.