Hi Banner1976, or may I call you Yatsek?
I've had a look through the "second attempt" series, most were shot wide open at f1.8, so all you are really doing is practising focusing. To get the hang of depth of field (DoF) and what it can do, you are going to have to be more adventurous
A prime example where a greater depth of field would help is he last but one (penultimate) picture in the series; the one with two people, in the foreground (your sister I gather?) and someone behind her.
In this one, you have set the focus between the two and if only you had shot this with a narrower aperture, say f16, they would both have been a lot more in focus.
In the shot before (of same two people), you had focused just on the girl and that is a good use of narrow DoF, leaving the chap behind well out of focus.
Hope that helps,