The best advice I can offer is to set as your main target, finding a river that you can fish regularily - any half decent river will keep you busy for at least three seasons and maybe many more as you learn the basics of river fishing.
Preferably a river that does not restrict the use of methods.
Before you start listening to advice on drag free drifts, moving dries, french nymphing, nymphing, fishing wets, spiders, softhackles, emergers, etcc... start at the basics.
Trout eat food, and imitating that food will in the long term give you more success than fishing arbitrary flies and methods. Find out what fly life exists on your chosen river. Find out when the hatches are likely to occur. Find out how the trout react to the various hatches. A lot of research on the internet will provide a lot of information on this.
This excerpt is from a very old book and the advice contained is as good as it gets - any angler that follows this advice will save themselves years of pissing around.
From Cutliffes, Trout Fishing on Rapid Streams - book available at www. archive.org
From the habits of fish in small and rapid streams will we deduce our principles for founding our ideas of fishing these streams, and the more fully we comprehend this portion of our subject the more correct will our reasonings be, and the more fruitful our labours prove.---Let us endeavour then early to form sound and correct opinions of our subject; let us not be guided or governed by the dogmatical statements of one person or another, as to what method is most suitable to our field of operations, let us not be biased or limited in our attempts by the authoritative and often too positive assertions of others, but rather having formed our own notions on correct and just grounds, let us bring them early into practice and strive to steer a course as free and independent as the right knowledge of a subject demands; we shall then be better able to judge of what others say, to refute their errors, and profit by their experience and statements when they have been justly and reasonably considered.
another that is worth a read
American trout-stream insects : a guide to angling flies and other aquatic insects alluring to trout : Rhead, Louis, 1857-1926 : Free Download & Streaming : Internet Archive
Next bit is doing some general reading on where trout can be found
Reading Rivers, Tracing Trout
Reading the Water | MidCurrent
Find an angler or several anglers on your chosen river that will spend a few hours with you - BUT do not accept anything he says as being FACT. Facts only are fact when you have proved them so for yourself. If you blindly accept what everyone says then you will spend many frustrating seasons, for in my experiece at least 60% of river anglers really do not have a clue and less than 5% really know their craft. The biggest difficulty is differentiating b..sh.it from reasonable advice.