To me, consent is getting and giving permission to do something that may make anyone uncomfortable or a way to offer help that may or may not be needed. Consent can be given for a range of activities, such as holding the door for someone to hugging to getting intimate. A lot of people don't realize how big of a deal consent can be, or rather, how big of a deal crossing a consent boundary can be. They also don't realize how easily it could be prevented in the first place.
The key thing about consent is communication. This not only means verbally talking about it, but being able to read body language and even noticing the differences in people's tone of voice when they speak. I know this sounds fairly intense, but anyone can do it. Remember: where there's a will, there's a way. Talking about consent can be a bit intimidating in any situation, more so in an intimate one, but it's to better improve the time and activities shared for all involved. Trust me, it pays off!
Think of a time when someone did something that made you think, 'Did they really just do that? Couldn't they have asked if it would be okay to do that?' How did it make you feel? Did it ruin the rest of the time you shared with that person afterward? Most importantly, did you tell them how it made you feel? A lot of people don't realize that they should say something when a boundary of theirs has been crossed. This is also where communication comes into play, especially in a more involved relationship, such as a one with a best friend or lover. It may be scary to stand up for yourself and say, "Hey, I really didn't appreciate when you did this without asking," or, "You know, I really wish that you had talked to me before you did this," but unless you actually tell them, they'll never know and may continue to cross boundaries. Some people are afraid that saying, "No," or refusing a proposal of any sort might cause problems with the relationship they have with the other parties involved. But what's more important? Keeping quiet and uncomfortable to save the relationship, or standing up for yourself even if it means losing the relationship? I'm hoping that all reading this chose the latter.
So that touches base a bit more with familiar people, but what about consent with people you hardly know or don't know at all? It still works the same! Sure it might come off as awkward (and potentially pretentious) to let someone new know that something they did or said has made you uncomfortable but, again, if you do not inform them that a line has been crossed, they won't know and may continue to do so. It may also seem silly to ask, "Can I give you a hug?" but it definitely shows that you respect this new person, and the majority of the time they will really appreciate the gesture. If they don't, then most likely they are either uninformed to the concept of consent, or they choose not to embrace the concept which could lead to problems later on.
During the process of writing this, I was talking to a friend of mine who thought I should mention briefly, in detail, on how consent works with an intimate partner. Specifically, they asked me, "How does asking for consent work with each step? From kissing to touching to, well, you know?" My advice for this is to have a talk with the person that you're becoming involved with first. Discussing personal boundaries you and them have is a good way to start. The zine that was linked before has a great section with multiple ways to initiate such a conversation. My favorite one that I came across there was, "So, I make it a priority to be upfront with people (especially with people who I care about)..." From there you can talk about your own boundaries, and then prompt them for theirs. If they aren't willing to open up right away, it's okay. Some people are highly sensitive when it comes to these kinds of things and they may want to build trust before they can even think about talking of such a topic.
Now, being able to sit down and talk beforehand would be an ideal situation, but sometimes things can move really fast, such as meeting someone on a night out. Don't ever, ever, EVER hesitate to pause the action to talk about boundaries and consent! "I'm really into you, but before we go any further I want to check in about a couple of things..." or, "I really like you, but I have some things I want to discuss before we continue..." are good ways to do so, followed by what you feel comfortable doing at that point in time with them. Then if you plan on continuing to be intimate with them, you can have a more in-depth boundary conversation later.
Keep in mind that while you are in the middle of things, it is perfectly fine for you (or them!) to say if something makes you uncomfortable, or if you really like something. Some people have a safe word system in place where if something makes them uncomfortable, they just say a word (which is predetermined beforehand) and the other person will stop whatever it is that they are doing. You can also use the same type of system if you really like something and would want more of it. Again, it would be a predetermined word discussed beforehand.
Also, there is no problem with asking, "Is this okay/do you like this?" or, "Can I touch you here?" It's better to ask and get a positive answer than to not ask and have crossed a boundary!
And the last rule of thumb that I keep when it comes to consent is to always, always, ALWAYS ask permission before touching someone you are not close to (and even at times with people you are close to)! Failing to do so can cause issues and potentially drama. On the flip side, don't ever, ever, EVER hesitate to let someone know if they have made you uncomfortable by touching you, or even by the things they may say! Everyone has the right to exist comfortably in any space.