I'd suggest (unless you want to dive into DIY right away, which I definitely recommend, but I think there are some good reasons to try some storebought first, some of which have already been mentioned, including the fact that your tastebuds will be regenerating, and DIY is easier if you have SOME storebought experience first to at least know what types of flavors you may like as you start out, and etc.
There are many vendors that will sell small, inexpensive sample packs, that are pretty good. ITCvapes sent me a sample pack and while it was (by then somewhat too sweet for me, but I've been DIY for some time now, and my flavoring requirements are different) pretty good, most of the juices. But lots of companies will do it, and honestly sometimes going to one vape shop, if they follow their own processes and flavoring, well, they may use primarily one "set" of flavor companies, often the same nicotine (which can vary in quality) so it may be easier to try some (small) online options from different companies and get a sense of what you like.. My husband likes NETs from Heather's Heavenly vapes, and they are a solid and reliable juice brand, although there are like, ,infinity more.
You could also start DIY by seeing if you can "amend" juices not to your taste, either by dilution with PG/VG... depending, you may need to have some nicotine on hand in case you need to dilute a fair amount, or by adding another flavor to round it out, etc. That can sometimes be useful, although I tend to amend juices that I get commercial often by dilution as typically, flavoring is too strong for me now, but often a commercial juice may mix well with a DIY standalone I have created, etc.
I've gotten fairly good at "rescuing" juices (both my own, early attempts, but also storebought) and I did it with slow, steady patience. Lots of tasting and experimenting with different flavors, then starting with single flavor mixes I would "mix" in my tank to get a sense of steeping time and how my flavor blocks "play" with each other.
Most of all, write everything down. DIY is both an art and a science, and so is finding the right juice, so once you decide on an approach keep notes on "everything." By the time I got to DIY I pretty much found a set of "tastes" that I "like and dislike" and that really helps me as I continue to DIY. But, everyone's taste is different, so approach it like a... IDK, summer project? Start researching, tasting, annotating and etc., and try some early experiments!
I do know (100%) that I can mix flavors to MY palette better than a commercial juice outfit (and I can also mix for others, but I usually start by having them pick a primary flavor, send them away) and then overflavor (for my taste) and slightly oversweeten (for my taste) and haven't gotten complaints . The kind of people I give them to won't hesitate to complain, either, so I know they genuinely liked them.
Building blocks of flavor was my key. That and starting slow and reading and tasting a lot of different things and recipies. I'm fairly confident in my juices now, but there is always more to learn and experiment with.
I like Nicotine River for DIY. I like their nicotine, and everything always comes clean, organized and etc., and they do have a good selection of flavors.
You can do all of this (to varying degrees) at the same time, or you can start with storebought and work your way to DIY.... But if juices aren't tasting "great" to you on a consistent basis, over time, in my opinion (as always) DIY can work just as well, if not better, although it does involve some early outlay and willingness to experiment.
Best of luck, I hope you find some juice options you like!
Anna