For guys/tops: Pace yourself, learn some foreplay techniques that can keep your partner aroused when you need to break or slow down, and generally don’t allow yourself to go full bore until you think it’s a good time to cum. A lot of this is really just learning what your partner likes and enjoys, and experimenting to find different ways of doing things. Can they get off from their chest/nipples? Do they their butt being touched, groped, spanked or fingered? Is there a particular way you can grind against them, penetrate them or thrust that keeps you aroused but doesn’t stimulate you, but gets your partner closer to their next climax? If you feel like you’re going to blow too fast, suggest changing positions, use that break to clear your mind some and reset while your hands and mouth keep your partner stimulate and your dick gets a bit of a break.

Outside of sex with a partner, you can edge/tease yourself to improve your sexual stamina somewhat. If you’re jerking off, don’t get yourself to cum soon as possible, but build up a rhythm and take semi frequent breaks. Staying hydrated and exercising regularly also did wonders for my bedroom stamina.

Best solution I’ve found is just do it twice. Cum however fast, slow down, tune into your turn ons to keep it up, and then just keep going. No “tricks” work well, especially not without making you enjoy it less.

Assuming you have a penis

Patience and pacing. Go slow and take your time, especially at the start. “Too much too fast” will usually accelerate the end of the fun.

If you feel yourself getting overstimulated, take short breaks as needed. Applying pressure to your prostate through your perineum can help calm things down if you’re approaching the “point of no return”. You can practice this yourself (it’s often referred to as “edging”) or with your partner, for the latter it’s important to communicate where you’re at and what’s going on so they’re not confused.

If it’s been a while since you’ve had an orgasm, getting one taken care of beforehand (either with your partner or before) will set you up to last longer the second round.

None of these are “immediate” solutions so it’s important to exercise patience and prepare your partner to do the same. With practice, you’ll condition your body to less overstimulated.

Practice

I know that it sounds like I’m being silly, but take your time to pay attention to what your body is doing, what it responds to etc.

You can then start to control it a bit more

It’s not difficult to do, but don’t overdo it

I have basically conditioned myself not to cum until my woman has. Occasionally she does something that trips my switch quickly, but it’s very rare

It may sound great (and it mostly is) but when she wants it to be all about me, I have a hard time really relaxing into it

Assuming you have a penis, try positions where your knees have to be bent.

I find it easier not to cum when my partner is on top, so if I’m particularly horny, we’ll start off with me on bottom so I don’t pop too quick.