How do you increase your red line??

at the micros your redline should be negative as most of your ev comes from value betting, but if you want to increase it for some crazy reason, start 3b a more polarised and generally wider range and up your af, but i would highly advise against this if you are already winning at a decent rate (8bb/100+).

Don’t fold, ez

Look into your game from both blinds (stealing from sb, defending from bb) and also into "mandatory bluff" spots and lines i guess.

1) stop folding period.
2) 3b more preflop, squeeze more preflop, 4b light vs light 3bettors, 5b light vs light 4bettors
3) steal more in button/sb, resteal in bb/sb
4) cbet + 2 barrel more
5) go to showdown more
6) start thin value betting
7) start bluffing
8) start betting bigger with your value hands
9) stop calling flop cbets/raise just to fold to a turn bet
10) start check/raising flop and/or turns with pure air or value or draws

Well it depends why it's very negative, but yeah pretty much what dangromango said. Overall just increase your knowledge- see where your leaks are, where you don't apply enough aggression and study those.

Basically if you increase your overall poker understanding and skill it will come naturally.

Bet when they check, raise when they bet.

Attack capped ranges