I'm 53 years and started playing Chessity just over one year ago. I learned to play chess from my father but did never seriously practise and hadn't played since the age of eighteen. I entered Chessity at a level of 1200 ELO points and grew in one year time, with modest but consequent training to a level of 1700. My target for the coming year is to reach 1900. Just by training through solving puzzles. I have worked a lot with Chessity but only with the TPR en mobile games. To help you improving your use of Chessity I will post my findings here from time to time. I hope they are helpful.
My first training advise is : do not canonize your rating
After playing for a little while you tend to start staring at you rating. You only want it to go up without going down. This keeps you from solving many puzzles. You might even be tempted to take 20 minutes for solving one puzzle or opening two accounts (the training one and the sacred one).
Don't be afraid to make mistakes. The learning process goes much faster if you try to solve more puzzles. Your rating may go down in the short run but it will bounce back to a higher level before you know. My rating was all over the place in some weeks but it tends to creep upward in the longer run.
After a while try the errors training module. Here your last mistakes are shown. Playing the "errors module does not affect your rating!