Hey anon! This is a beginner trying to help out an advanced artist - lets see if I could help. I cant help you with how much of the tricep or elbow you will see but this is a technique to help meassuring the tricep and biceps. I am recently learning to draw the arm in perspective, so foreshortening is a huge deal for me right now. This is what I have learned (watch the image): I had to draw the arm on top of the cylinder - the red marks represent the arm of a male. As you can see the triceps goes 1 1/2 segments down the next peak starts at 3rd segment goes out 1/2 a segment and in 1/2 a segment. On the otherside you will see the bicep taking 3 segments start to go in after 2 segments. I only draw male figures which are 8 heads tall - never jumped into other scales yet. And here is a quick summary of important landmarks I use in general. 1 ⅓ Heads - Shoulders - Collarbone 2 Heads - Nipples 2 ⅔ Heads - Bottom of ribs 3 Heads - Elbows - Waist - Navel 3 ⅙ Heads - Obliques 3 ⅓ Heads - Top of the hips 3 ½ Heads - Outer curve of hips 3 ⅔ Heads - Top of leg 4 Heads - Crotch - Wrist 4 ½ Heads - Hand end closed 5 ½ Heads - Top of knee 7 1/2 Heads - Top Ankles Hope it helps. Best regards Alexander

I don't have advice for you. I find it hard to remember too, but like you said, with time it gets easier. A lot of times I just feel/observe my own arm if I forgot something.