While there are no guarantees, I wrote out my strategies. Please add yours in the comments.

Waiting for sex of course. If he ever begs or complains whines cries or makes accusations (you don't love me) trying to get you to have sex with him then you definitely need to dump that guy.

I also recommend getting him aroused and then not having sex with him several times before ever having sex and occasionally after. See how he reacts.

Several times have him pleasure you (oral/manual) and then don't reciprocate. See how he reacts.

Never have sex with him every time he wants it in the relationship. Make sure to say no sometimes and use that for vetting.

Search his phone and find any porn that he has or sexual conversations, fetishes etc.

Always ditch man who watches porn, goes to strip clubs or has sex with prostitutes

Also men who have conservative views of women are much more likely to be rapists

Avoid drug addicts and alcoholics. Even men who come home drunk occasionally are a risk.

Vet his friends. They should also be high value. They shouldn't be making misogynistic jokes, rape jokes, being low value together

When you do have sex he should always care about your pleasure and any pain or discomfort you feel

Several times when having sex pretend you're having pain or discomfort and you want to stop. See how he reacts. Also say that you have pain but don't mention stopping. See if he mentions it and stops. He doesn't get points just for mentioning it, only for actually stopping. You could even try saying it's okay and he should of course decline to continue anyway.

You could pretend he hurt you and see his reaction. He should immediately stop, look very concerned, hold you and comfort you.

Edit to add:

Play dumb about rape allegations. Mentioned some from the news. Mention rape stats. See how we reacts and what he says. Don't give your opinion, let him out himself.

Courtesy of u/whiskey_and_oreos

Pay attention to how that first kiss goes. Asking for consent is the bare minimum.  Pay attention to those hands. Things like touching your back too early in a crowded restaurant, a hand wrapped around the back of your neck (he's literally controlling where you look), etc.  Any comments or jokes about the "three date" libfem rule.  When you do have sex, if you want something to change (like a position switch) and he keeps going, that's a problem. Additionally, if you tell him to continue doing something and he changes it up, that's also a problem. Both of these point to him not understanding consent and autonomy.  If he keeps you awake at night or wakes you up because he's hOrNy, that's coercion and abuse in the form of sleep deprivation.

Courtesy of u/moira_spice

Also I'd like to add that you should say no sometimes for milder stuff like kisses or cuddling. Say that you're not really in the mood for that, and then see how he reacts to your refusal. Is he pushy? Is he negociating ("so maybe just a lil peck? So maybe just a hug?") If yes, he's more likely to push your sexual boundaries later on.

One more note: clearly your first sexual vetting strategy is not to be alone with him and start sexual acts and then stop them. Obviously vetting for things he might say in conversation, his views on rape, whether he can take no for an answer or if he's too touchy on a date all would come well before private sexual situations. Again I'd like to remind the newbies that sex isn't happening for 3 months. That's 3 months of time that you can vet this person before ever having sex. Or more if you want.

And another note: to the women saying if you turn on a man or get and orgasm from him that he will rape you if you don't continue or reciprocate so don't do this. At some point in the relationship you will want to stop during sex or say no to sex. What then? At some point this situation will arise. What is your strategy here? To just never say no? That's not consent that's just a societal form of rape. When we discuss all men benefiting from male violence this is one of the things we're talking about. Women having sex they don't want because they don't want to be raped. Considering I've been in both situations I can tell you there's not that much difference.