Since I learned relatively late in life (mid 30's), I've been meaning to put together a guide or a blog post on this topic. Maybe this will be my template.
TIP #1: Learn on a powerful car such as a V8. You will have to learn to use your left foot to work the clutch, and it takes time to build sensitivity. You've been using it for nothing up till now, now it has to do some actual work. On a powerful car, you can worry about working the clutch by itself. On a less powerful car, you will later have to learn to get the revs up while working the clutch and if you're just learning how to work the clutch pedal, you're going to stall out a lot because you're not used to working both feet simultaneously.
CONCEPT #1: When you drive an auto, you're used to stepping on the brake and then getting off the brake when you're ready to go. The car is always "in gear". In a manual, you must remember you can and will stall the car if it's in gear and the clutch is engaged (unless you have a really powerful car).
CONCEPT #2: When in neutral, the car will roll backwards/forwards, so learn to use the brakes and lean on the e-brake for help.
CONCEPT #3: The clutch is not an on-off switch. Go slow and you will learn the "engagement point", where the clutch and flywheel make contact and engage, and it's a curve not an immediate engagement. So getting into 1st is not a button push, but a gradual application of the clutch pedal from 0% to 100% engagement. If you put the car in gear and just release the clutch all the way, you will stall most cars because the transition is too harsh. Learn the engagement point and make your clutch release gradual but quick.
TIP #2: Do not preselect gears when you are in neutral. E.G. you're in fifth gear cruising and then take an off ramp and decide you want to be in 3rd at the apex, you might think you can depress the clutch, take the car out of fifth and immediately put it in 3rd, and keep the clutch depressed until you are ready to engage 3rd. Don't do that. You would think that having the clutch depressed is the same as being in neutral but it isn't. Even with the clutch down you will still have partial engagement and you will grind the gears. Keep the transmission in neutral until you're ready to engage the new gear.
TIP #3: Practice your shift gate pattern. Most cars have reverse on the lower right, but some cars like BMW put it in the upper left. You shouldn't have to worry about accidentally hitting reverse (I think most cars prevent this at speed, and they usually make it difficult to get into R). I had the hardest time finding 3rd (nervous about rowing up and down, hitting 3rd instead of 1st or 5th, for example). My tip for hitting 3rd is to open your palm and push the stick forward, you'll hit 3rd in the middle every time.