How do you know if a guy likes you?

Men don't normally announce their emotions. It's mostly due to a fear of rejection, or because they don't want to be perceived as being weak. They will most likely show interest by starting a conversation, getting to know you more , and then asking you out - it's at this point that a lump appears in his throat, as that gives women the chance to reject the men.

Unfortunately, some men hone in on the physical attractiveness of the lady to the exclusion of other attributes. If you don't want that kind of attention, then you have to dress modestly. An attractive lady will still be recognised for being attractive if she dresses modestly, but by doing so she'll keep away unwanted attention.

From my perspective, the ladies I have fallen head over heals for have been average looking, but with wonderful, engaging personalities (probably the most important thing to me, apart from being a christian, the most important thing to me these days).

Is he willing to invest himself, his time, and his life, in you?
Any healthy long-term relationship requires investment of four aspects of a person. Many people settle for the physical aspects, robbing themselves of the most important and wonderfully rewarding parts. The physical aspects of a relationship make up less than 20% of a healthy one. Whether manifesting as affection, caressing, kissing, sex, etc., this is still the smallest part of a healthy relationship.
The mental aspect of a relationship makes up around 25% of a healthy one. This includes the decisions to take the risks involved in initiating, maintaining and developing the relationship. It also includes the choice to discipline your thoughts so you won't agree with the adversary when he starts reading off the list of faults he knows about in the other person. Normally, the enemy will wait until the infatuation starts to wear off, so the potency of his accusation will be more effective. Another trick he uses that we have to actively guard against is the desire to equate someone their behaviors, attributes, attitudes or lowest common denominator. The enemy points out that the other person is stupid, lazy, etc. as if that label defined the person. This aspect is often simpler for women than men, since men tend to function in this realm more naturally.
The emotional aspect of a relationship makes up around 25% of a healthy relationship as well. This includes the infatuation, feelings, emotional intimacy and more. If the you are willing to recognize that you have feelings, and invest in figuring out what they are, and developing them, you will do well in this area. Men tend to be hindered in this area, where women tend to function more naturally. For this reason, if a man is willing to function emotionally, they tend to do so more simply, since they don't invest as much time developing mechanisms as they grow up.
The largest (over 30%) aspect of a healthy relationship is spiritual. This is the part where you interact at depths of your beings that go further than anything most people experience on a regular basis. This is where you enjoy just being in the same room, without physical communications, or with eye contact where you allow your hearts to interact directly, without the distraction of the body. This level of intimacy is also the ultimate level of vulnerability, since all the barriers you have ever developed fall and only God is left to protect the person He made you to be from the person He made them to be. In a healthy relationship, this can be a major time investment, which is always affirming and edifying, even if it is not rational, emotional or physical. It is also the most rewarding level of relationship, because it is where you are truly not putting on masks, or protecting the your self, anymore. If you protect your self from potential pain, you are also protecting your self from potential joy.
A man who will invest like this, in you, likes you.