Ah I’m so pleased I didn’t speak out of turn 
sometimes i feel like the cgm is a bit like a cult (tbf some of the fb groups there are for curly girl method would seem to back this up) but i have wavy hair too and did battle with my frizz for years so believe me i do feel your pain.
If you really want to start, you don’t have to spend tons. Cheap cone free conditioners are everywhere! Tesco do one called extracts which is 80p and perfectly fine. They also do another own brand one called keronics which is apparently cgm friendly, but I haven’t tried it personally. Wilkos do one at 80 or 90p but i’m sorry, I can’t remember the specific name of it - think it’s their own brand one, again i personally haven’t used this. Poundland/savers/b&m/home bargains type places stock a brand called xhc which do a banana one and a ginger one that are great. Garnier ultimate blends conditioners are silicone free and so is the hair mask they do for deeper conditioning. You can use the same conditioner to both co wash and condition/detangle with, and as a leave in if you want, it’s fine.
I know a lot of people feel like co washing is not for them, but don’t knock it till you’ve tried it. You just need to remember that since you’re not stripping hair chemically, you need to do more to release the dirt mechanically - so that means really working the conditioner through the scalp and giving it a good old rub to get the normal dirt and sweat and old products to come free, but without scrubbing pr ragging at the lengths. I have one of those cheapy silicone ‘shampoo brush’ things you can get off amazon for a few quid just purely because my arms get tired (and am a hairdresser so wash hair all day and it gets to evening on wash day and i really can’t be arsed faffing endlessly with mine 😂)
So, yeah, give scalp a good working over with cone free conditioner or if you really don’t fancy co washing or feel like it weighs your hair down, sulphate free shampoo - these are harder to come by on a budget. All the brands i mentioned above for conditioner being cgm friendly, none of the shampoos are, so be careful. You can use a site called curlsbot.com to check ingredients if you’re unsure. Johnsons baby top to toe wash (NOT the baby shampoo, the all over wash) is sulphate free, so are all the Yes to... shampoos (available on amazon, i have the yes to carrots one)
So, rinse out then condition again as normal. Detangle with your fingers. Squish the conditioner in with water - you’re trying to get moisture into your hair, so squidge squidge squidge. Then rinse. To stop the water knocking your waves straight you can hold your hair up to your head as you rinse, but, real talk, i always forget to do this. Then you can put a tiny amount of the same conditioner back in your dry ends as a leave in
Gently squeeze your hair, ever so gently. Don’t use a terry towel, use an old t shirt or microfibre towel and wrap it up while you get dry and dressed. Then let your hair down and give it another gentle squeeze, and apply a bit of gel if you want to define your curls, the umberto gianni curl jelly is decent. To do this, wet your hands, put a bit of gel in them, rub it together then smooth it down the length of your hair with ‘praying hands’ (exactly how it sounds). Do this on each side and the back. Then dry naturally or diffuse on medium heat and medium speed max.
In general, try to go a bit longer between washes. You can ‘refresh’ your hair with a bit of water in a spray bottle and a bit more gel if you like between washes. Try to avoid yanking it out of your bag strap/seat belt etc, you might feel that it’s no biggie to do this a couple of times a week but clients are always gobsmacked when i say ‘do you wear your bag on this shoulder’ or ‘do you drive a lot’ and i’m right, and it’s because i can feel their hair is shorter/thinner on one side.
At night you can sleep with it in a buff type band , or by ‘pineappling’ it up at the very top of your head loosely in a silk or satin scrunchie, or you could get a silk pillowcase, or a silk or satin scarf and put this over your pillow, to avoid it being all rubbed rough.
I know this sounds a lot! And overwhelming. But honestly i wash my hair once a week, i use 3 products max when i do, and on a morning i just spray it down and leave it. Once you get the hang of what works for you it’s way more simple than being in constant conflict with your natural texture.
So i’d give it a go, start simple. If you have insta have a look at powerdomi, marisascurl, curlycailin and mestizamuse for product application and drying tips - how you handle your hair is really important, more important than using £££ products imo. If you don’t have insta, look at them on youtube, or curly cailin has a blog. find people to follow online whose texture is similar to yours, so of similar ethnicity to you. Curls and beauty diary is good if you’re south asian, she’s on insta and fb. Cailin and domi are irish - it’s funny how different heritages’ curls behave slightly differently.
Sorry for the essay! I just get excited about natural hair. Good luck.