Hi, until what ELO is it reasonable to onetrick openings in the time of modern opening prep? I'm not asking about possible, but reasonable with the aim to maximize progress.

On Tuesday I'm playing against an opponent who will likely play the London System.

I'm rated 1700 Elo and I don't know how to prepare my opening: there are too many variations and I'm not sure which one to choose. d5 and a quick Bd6? King's Indian? Nf6 and c5?

What software and tools are typically used?

Hey everyone, tomorrow I am playing the first game of seven of my first OTB tournament ever.

It is classical chess so I'll probably end up playing for some hours.

Do you have any suggestions?

Thank you!

I enjoy looking at tournaments and playing guess the move through games. I would like to do this with The World Youth Championships and annotate the games. However, once I have finished, I don't actually know how to use the time I spent to improve my game. Sure I can put the engine on but I don't think that helps me for strategical mistakes. Any advice?