what's a typical approach for you with haircare?
since i don't know much about how you care for your hair, i'll just go down the list based off what i do with mine.
do you make sure that before you wash your hair, your hair is detangled thoroughly? if it's not, do you detangle on damp hair, or dry hair oiled? there are different methods. it's best to finger detangle only, if you're not already doing so, but if you choose to use a comb, do you first section your hair and then, with a wide-tooth comb work through the small, workable sections from the ends of your hair to the root on hair that has slip, either by conditioner or detangle spray or just water, or whatever floats your boat? the point is, it shouldn't be crackle dry, because that would cause it to break, which you would be able to hear, see and feel in any case.
next, once all your hair is detangled, are you washing your hair in sections? shampooing the roots, as needed, or just cowashing? if you have really thick hair or very long hair, washing in sections is best because it keeps the hair from matting and tangling all over again during the wash.
i don't wash mine in sections right now because it's not yet long enough to warrant it, and when my hair is drenched in water, it actually completely loses volume and goes silky. but if my hair were, say, midback, it would make more sense for me to wash in sections.
so use judgment on that one.
when you wash, are you gentle, taking care to not scrunch your hair over your head but rather washing with your hair's naturally-falling tendency so as to reduce likelihood of tangling?
next, once out, make sure you're drying your hair by merely sitting the towel around your head. don't rub it all around, as this can tangle it and/or break it altogether. just let it sit around the head and absorb. the other method is to get a microfiber towel or a tshirt to dry your hair with, but even with these you still don't want to rub them around your head all haywire, for the same reason.
next detangle your hair again. this detangle should be markedly quicker than the pre-wash detangle, simply because you don't want your hair to get tangled again by allowing it to dry naturally without beind set.
at this point you have options. detangle and blow dry. detangle and twist. detangle and band. detangle and braid, whatever.
just don't let it dry wild because you. will. regret. it. LATER. lol
and at this point you moisturize it with your moisturizing agent of choice, with your preferred method. most people recommend moisturizing and sealing, which i don't practice, personally, but many find it crucial. moisturize your hair post-wash whenever it starts feeling dry. and it's best that you choose a protective style to keep your hair in, one that will preserve your hair's moisture so that you don't have to re-moisturize all the time, and one that will keep your hair from tangling, too.
for me i twist my hair as i detangle after a wash, and when those twists are dry, probably by day two, i take them down (twistout) and throw the resulting twistout into a high messy ball. i call it a messy ball because it's not a proper bun. it's not truly messy in the sense that it tangles, because i basically don't touch it unless it starts getting wild or sections start springing out of it.
but there are plenty of options, like twists, cornrows, braids, wigs, extensions, finger coils, curl definining, updos, etc.
but the point is that you want to set your hair before it dries so that it doesn't tangle.
pick a style and try to stick to it for at least a few days without redo. or if you do have to redo it, make sure you are gentle and that it's a style you can take down and reinstall without breaking your hair. you should never incur breakage on healthy hair through mere styling.
breakage while detangling is to be expected, but even with that said, if you're getting more than about 5-7 strands of BROKEN ends that's a problem and a sign that you could stand to be more gentle or add more conditioner/oil or whatever you prefer to use.
i recommend a style in which your ends are tucked, and some ppl will stay in a style for a week to several weeks without taking it down to detangle.
personally if i go about 5-6 days without washing my hair, i'll usually detangle my hair somewhere between that interim. usually by day 3 or 4 i'll detangle, which is good for my hair because i'll have accumulated a ton of shed hair in that time.
so your regimen should address the regular removal of shed hair.
next, some ppl will promote a night time/morning r outine, and this is up to you to determine if your hair needs it. mine doesn't, and i tend to sleep on my hair in whatever daily protectrive style i've chosen, mostly on a satin pillow, and i usually don't do anything to my hair when i leave the house. i work overnight shift, so it's not that serious lol
another thing i didn't mention, because i personally don't do it as my hair retains moisture pretty well all its own, is deep conditioning. if your hair needs that or protein treatment, there are plenty of simple self-tests you can do if you search on the internet to see if your hair qualifies. generally if your hair is prone to dryness it's best to deep condition as much as is needed, and if it is susceptible to breakage and generally weak, most recommend a protein treatment.
generally speaking you can't really deep condition too much, but it is very possible to overdo protein, so proceed with caution as to the latter.
i think i've covered all of the main points on hair's health/care.
so far as you wanting it straight is concerned, that's another matter.
i recommend flat ironing no more frequently than once every other week, and when you do flat iron, MAKE absolutely certain you're using a quality iron. i prefer solid ceramic irons, such as FHI and CHI and HERSTYLER, but there are other top brands to choose from. if you use a crappy iron on your hair, don't be surprised if over time you find yourself having to trim a lot more.
refer to others' advice on the use of heat protectants and oils and all that, because when i flat iron, i flat iron bare, non-producty hair, as that is my preference so far as the feel and sheen goes. product weighs my hair down, so i opt against protectants. but there are many ways to get straight hair that don't involve heat. you could try curlforrmers, flexirods, roller sets, banding, etc.
these are the more popular choices.
if you do flat iron, many will advise against using high heat, but i personally prefer high heat because it gets me the results i want quicker. silky straight hair. for that i don't recommend going over 410 or so, but you don't want to have to pass the iron over the hair section more than twice and if you flat iron make sure you are using small section. as small as you can, so that the heat gets reasonably distributed. this minimizes the chances of you flat ironing the same section a bazillion times.
make sure you flat iron on hair that has already been maximally stretched. i prefer blow drying for this, but roller sets would be probably a better option than blow drying for this one. this is because if you flat iron curly hair, the same exact effect happens as when you take a regular clothing iron and iron wrinkles into your clothes. you do the same thing if you flat iron over hair that has not be stretched as well as it could be. and this WILL lead to breakage and midshaft splits and all those maladies that usually come back to bite you royally in the butt many months down the line after you've swore off heat.
so pay close attention, use the right technique and handle with care, and as time goes on you'll improve.
as for combing and brushing, i do neither because it has been proven that combing and brushing wears away the hair's cuticle over time, and if you're trying to grow your hair long then i think minimizing the use of either tool or preferably, eliminating it altogether, is your best security against weathering of your ends and therefore leads to optimal retention down the line.
maybe others can offer more information to address the dryness you're experiencing, such as maybe about baggying, which i know nothing about; but i'd be willing to bet your hair is as dry as it is because of the heat.
and if that is the case, you should take a break from it for a few months just to see if you notice any change. when i took a break the difference in my hair's thickness and elasticity after two-three months was like night and day. not to mention my length retention was out of this world for that span of time, even though the heat damage incurred from previous use came back to rear its ugly head.
any more questions, just ask and we'll do the best we can!