After bleach care suggestions (also protein filler ?)

I'd use the protein thingy once between bleach baths, but don't leave it on any longer than the instructions say, and follow with a good moisturising conditioner.  Too much protein can make your hair dry and brittle so keep an eye on the condition.
Avoid silicones in hair products as they just mask the hair's true condition and can build up.

In general, avoid heat styling and rough handling (like back-combing!) and watch out for things like zips, velcro and straps.  Might also be worth getting your own pair of hairdressing scissors and snip off any split ends you see. 
Oh yeah, protect your hair from the weather!  Don't leave it loose on windy days.

If you have been dyeing your hair red then the best thing you can do to avoid damage is to use colour removers rather than trying to bleach the old colour out.
Colour removers are excellent at removing permanent dyes and pretty good with direct reds IME, plus they don't damage at all, they are just drying which can be remedied by following up with a good deep conditioner.
Skipping this step and going straight to bleach will definitely cause more damage long term.

Sorry I guess I should have added more detail - I have already used color removers 🙂  Bleaching was definitely not my first step, that's just where I'm at now!  I used color removers to get out what I could and now I'm doing bleach bathing to get out the rest!

kitebunny - thank you for the helpful tips!  I will make sure to moisturize well after the protein filler to keep it from being brittle!

Cool, that is definitely the best way to proceed.
Waiting longer between bleach baths is a good idea, the longer the better really.
I would also use coconut or argan oil regularly, overnight coconut oil or coconut and olive oil soaks are also good. If you are concerned about using protein, try mayonnaise instead, it has protein and oils so less likely to make your hair brittle.
You can also check the true condition of your hair by washing with clarifying shampoo, no conditioner and letting it air dry. Check that it isn't stretchy or mushy when wet or brittle and breaking when dry.
Slow and steady wins the race when lightening hair. I took about a year to go from permanent black to platinum blonde, but I had minimal damage. My avatar pic shows my hair after a clarifying shampoo and no conditioner or oils in it.

Thank you!!  I actually did your suggestion as I was ready for a shampoo anyhow and did a clarifying one with no conditioner or treatment or anything.  I let it air dry and it looked in pretty good shape right now!  Frizzy (status quo for my hair and also the humid weather we're having) and a little dry at the ends but mostly soft and good texture.  No stretching, snapping, or mushy texture.

I use coconut oil pretty regularly, I've never used olive oil though.  Is a 50/50 mix of olive oil and coconut oil a good mix for an overnight treatment?  Thanks so much for the help!

Going to be following this post as I'm also trying to achieve a pale base. My goal is to dye with pastel colours.
My hair is super dry after bleaching and it is breaking in places  :'( I'm waiting til my hair recovers before doing anymore lightening, just toning for now.