I'm not so sure how much help I can really be since I'm pretty new at this too xD

What I can tell you though is NOT to make a baking soda/water PASTE. I now use a baking soda rinse every few days (2-3) with a LOT of water and as long as I conditioner right after, it's fine. It can dry out though, so watch out, it's not for everyone. I used to condition with an apple cider vinegar rinse and it was real good, but I ran out of acv and need to get more but have been too lazy (and recently bought a $20 conditioner that I NEED to finish xD).

Another thing I've heard of is mixing egg with water/lemon juice as a shampoo. I've tried it once, but I can't really give you any good or bad reviews on that yet. I'm giving it a few weeks before judging it.

As for co-washing, I've never noticed any significant pros or cons to that. I've definitely tried it long enough to know I'll use it if I don't have anything to shampoo with, but I'm just not a fan of it. It's not my thing.

So, basically, I use a baking soda rinse (LOT of water, little bit of baking soda) or egg/water rinse as shampoos (and skip shampoo maybe one day); and a $20 conditioner (sorry, I forgot the name of it, but it's not significantly awesome or bad. I can tell you the name if you want later) as a shampoo rarely and a conditioner daily.