Ten half-finished projects teach you how to start. One finished project teaches you everything else.

Starting is a separate skill from finishing, and only one of them shows you what you still cannot do. Every project gets hard at roughly the same place, just past the exciting beginning, and leaving at that point means you keep practicing the easy half over and over. Finishing drags you through the problems the fun part hides.

Take whichever one is closest to done and finish it this week, badly if that is what it takes. Start nothing new until it is out. The last stretch teaches you things nowhere else does.