check raise material

Hi coaches,

I'm a NLH player and I play on the moment on NL5 with a BR of 250$ and im planning to move up to NL10 when I reach 300$.

The redline is going down. The blueline is going up.
Over the last 12K hands I make a profit of 8bb/100 on 6max.

I am working really hard last 4 months on my game and reach 100K hands.

I think that I loose to much by just giving up and I want to work some time on bluf check raises so my redline is going steady or up.

What kind of material do you guys reccomend?
I cannot find much about this.

Thank's a lot...