Investing your money - Managing position size

In my previous post I`ve written about starting small and increasing your position size when you are profitable and now it is good time to solve next two problems:
1. When should You increase your position size?

2. How much should You increase your position size?
Few days ago I read  this words on twitter:
"Traders want "to trade for a living" but then act like they need to retire next month. Stay patient, learn the basics, manage risk & enjoy." ~Tradeciety Rolf
PATIENCE is the key and having PLAN of managing your position size as important as patience.
If you have a plan your emotions will be in control.
From my experience good time to decide weether increase your position size is at the end of the year after 12 moths of trading. If you are profitable increase your position size but not more than 10-20% and trade again. But it is me. What is your PLAN? Stop and think about it. Write it down, be specific answer this questions: When I should increase my position? How much should I increase my position size?
Trading should be boring (no emotions involved) and this is the way to make it boring