My easy 12-step program is based on years of field work and worrying about house guests.
1. Remove clothes. This is key.
2. For simplicity's sake, proceed without regard to gender.
3. For stall showers, go directly to Step 12.
4. For tub showers, memorize placement of towels. If necessary, remove from likely region of spray but keep within reach from tub. Decide which end of tub to enter and adjust shower curtain (inside tub, please) accordingly.
5. Place bath mat (if any) near tub. Check for nonskid shower mat. When missing, take extra care to find handholds (if any. These are especially welcome on tubs with higher sides.)
6. Be sure any soap or shampoo is within tub area but not in a built-in soap dish that fills with shower droplets and keeps soap mushy. Such dish, though, may be sturdy enough for handhold. (See Step 5.)
7. Try to analyze water-pressure and temperature controls, normally different from any other you've ever used. If tub's controls adjust water for shower, pay special attention to conversion lever, toggle, or pop-up to avoid premature showering. If shower head is not of water-saving design (this goes for stall showers, too), follow your heart for public-spirited duration and flow.
8. For two-faucet, two-spigot tub, see if shower control is separate, located somewhere above faucets. If not, metallic hose may be attached to two spigots with V connection and shower head balanced on frail bracket as high as you can reach.
9. For two-faucet, one-spigot tub, ascertain if both faucets open by turning in same direction. If not, memorize. This should avoid final hot or cold spurt with handles intended to turn in opposite directions. Other surprises can be avoided by pretesting, if shower head has fancy ring control. When operable, this may deliver punishing jets as well as gentle drizzle or ordinary downpour.
10. For single big control on one-spigot tub and shower, take time to determine which knobs affect pressure and which affect temperature, if indeed they differ. (See conversion alert in Step 7.) If water laps over ankles, it's not too late to ensure drain is open or consider shortening shower.
11. Assuming Step 4 was observed, post-shower drying can be purely intuitive. In cases of extreme humidity, rotate slowly in front of window fan where available.
12. Stall-shower users basically have to take care not to run into glass doors, sliding or swinging. They may want to check nonmandatory Steps 4 to 11 if any problems have come up. Otherwise, both tubbers and stallers should now be aglow and well prepared to tell friends how to shower away from home.