What can I do After Fast Castle strategy?

Hey Everyone!

Recently I've been trying to improve at the game because I want to play with my friends but they are a level above me and I struggle on their game difficulty.

I followed this guide for the Fast Castle strategy.

It has notes on what to do after and they seem to help but wanted to know what else could help me.

Things/Questions I wanted to know

• Extended Build order (if there can be one)
• Best defense tactics (Castle/Tower near TC, or anything like that)
• Is there any building I can rush that would help me most in the long run, and what would be the min I'd need to achieve that.
• What is a balanced economy look like? percentage wise, do I need more of one resource than another or should it be even

I am currently on struggling but doing ok in 1v1 against moderate difficulty, and my friends are playing Hard difficulty. Thank you!