I started reloading in 1972 and started casting bullets in 1973. The first two cartridges I reloaded were 9X19 and .38 Special.
First, I will second the comments above on good reloading manuals. The best, in my opinion, are the Lyman Handbooks; good factory-tested load data along with excellent tutorials on everything from the basics to advanced techniques and troubleshooting problems.
Primers: standard small pistol primers will do everything you need in both .38 Special and .357 magnum.
Bullets: I use hard cast lead bullets exclusively in .38 and .357. They do everything I have ever needed from practice and training ammo to hunting ammo.
Powders: I've probably tried just about everything over the years. Eventually settled on Unique for these calibers. Specific loads that have worked well for me:
1. .38 Special, modest load for regular practice is 4.5 grains Unique with 158-grain cast SWC.
2. .38 Special, "standard load" for field use is 5.0 grains Unique, 158 cast SWC or 150-grain cast SWC-HP.
3. .38 Special +P load is 5.4 grains Unique, 158 SWC or 150 SWC-HP.
4. .357 magnum "standard load" is 7.0 grains Unique, 158 SWC or 150 SWC-HP.
5. .357 "Lite" (range practice load) is 6.5 Unique, 158 SWC or 150 SWC-HP.
My revolvers range from a S&W Model 37 Airweight Chief Special, K-frames (Model 10 3", Model 64 2", Model 19 2.5", Model 66 4", Model 19 6"), L-frame Model 586 4", and N-frame (Model 27, Model 28). At various times these have handled everything from paper punching to small game and a few Colorado mule deer.
Still using pre-pandemic supplies of primers and powder. With homemade cast bullets I load all of these for 5 to 6 cents per round ($2.50 to $3.00 per box of 50). I still pay attention to this because I started reloading just to be able to afford shooting, and now that I can afford just about anything I want I can't break the old habits.