My number one suggestion is, if it is something you really want, make a mental habit to double-check when you get your way. This can happen first in your head -- yay they said yes! this means time to double-check. Do they seem as excited as I am about it? If yes, great, move forward! If they are ANY less excited than me, look at how I asked*, look at their body language, look at their phrasing. If it all matches up with go-time**, move forward. If not, open up the chance for them to decline*** by saying something like "you seem a little hesitant, is there something else you want to do right now?" or "what are you feeling?" or even "are you sure? we could always do [alternate choice]!" (that last one you need to say with happiness for it to be useful). If you discuss it and don't end up feeling like they are sure they want it, don't do it. Better to avoid an experience that turns out to be unwanted, even if that sometimes means you mistakenly miss out on an experience that was wanted.
And, frankly, better to only do things when people clearly state that they want it than to have murky communication as the default mode. I know some people would not be able to have sex in this case, but it's not your job to make sure other people have sex, it's your job to make sure you never violate someone's boundaries. If someone wants to have sex but is hesitant about the kind/boundaries/etc, that can be negotiated, but if you want to make sure you don't violate them, you can't have sex with them if they are unsure that they want it to begin with.
*did you ask with an easy way for them to decline? For example, did you say "can we get sexy?/ will you go to this party with me?" or "I'd love to have sex with you tonight / I'd love if you came to this party." The first is a yes/no and it is REALLY hard for many people to give a flat no. So anything that is not a yes or other excited affirmative, treat it as a no. The second is better, in my experience, because people can share their own feelings in return, instead of being pushed into having to do it or say no. Sideways-no is much easier for most people to say.
**go-time body language and phrasing differs for everyone, but some things that in my experience are clear signs of reluctance (thus NOT go-time) are closed-off body (arms or legs crossed, leaning away, toes or shoulders or face pointed away from you, physical barriers like knees or pillows in the way, not making eye contact) or answers like "okay" or "sure" instead of yes/yeah. If you're not good at noting body language, practice and double-check with words, or just use words.
***the more chances you give someone to decline, the more sure you can be that they want what you want.
More in-depth explanation on how to be careful with sexual consent specifically.