Falling in love is not like picking and choosing from items on a shelf. You cannot really decide who you will fall in love with. So it's not like we can say, "Don't be attracted to this person or that person" or even "make sure you're only attracted to this kind of person," because that would be very hard to do. Sometimes you fall in love with someone and later find out that they have some sort of secret sin that will badly affect your relationship. But it's too late at that point; you love them already.
The important thing to remember is that when you are choosing whether or not to romantically pursue someone, you must keep God at the forefront of every decision. And of course, prayer is a big part of it! James 1:5 says, "But if any of you lacks wisdom, let him ask of God, who gives to all men generously and without reproach, and it will be given to him." God will help you decide if this is the right person to pursue for marriage. (Also see: How do I know if I'm hearing God or just my own thoughts?)
Since every person is an individual and each situation is unique, then it is impossible to say that a certain person should be avoided or that another certain person is going to be perfect for you. The only exception to that is where the Bible instructs us not to be "unequally yoked" with unbelievers (2 Corinthians 6:14). That is, we should not get romantically involved with someone who does not also follow Christ.
In addition to talking to loved ones and friends who know you and who know the person to get a better perspective on compatibility, prayer is going to be your biggest source for answers here. I know I already said that and it may seem like a trite answer, but only God truly knows your and the other person's unique situations and life stories and whether or not it would work out well for you both. If you do not feel that you have an answer from God yet, then wait. He may be telling you "no" or "not now," and you need to be prepared for that too.
If you feel you have fallen in love with the wrong person for you or the timing just isn't right, then that's totally OK. Yes, it hurts, but you will be able to make it through until tomorrow. God will help give you the strength and courage you need to let them go (Isaiah 40:31; 1 Corinthians 10:13; Psalm 28:7). You may always have a special place in your heart for them, but if you know it isn't right, you must stand by your conviction.
Trust that God sees a bigger picture than you do. He loves you deeply, and He does not want you to fail in life or be miserable forever. But that sometimes means that He will not give us what we want when we want it because He knows the positive or negative results of our truest desires.
"Trust in the LORD with all your heart and lean not on your own understanding" (Proverbs 3:5). After all, He made you and knows what would make or break your heart.
Like the old songs say, sometimes you can't help falling in love. When you are choosing whether or not to romantically pursue someone, you must keep God at the forefront of every decision. Pray for wisdom (James 1:5), and be prepared for any answer—even one you may not want to hear. If you do not feel this is the right person, then ask God for the strength and courage to let them go. Trust that God sees the bigger picture and will not leave you to be miserable forever (Proverbs 3:5).
Cat is the web producer and editor of 412teens.org and loves to write novellas with local young writers at her workshops. She also contributes at GotQuestions.org, Blogos.org, and GQkidz.org. When Catiana is not writing or hanging out with teens, she loves spending time with her two kids, five socially awkward cats, and her amazing friend-amily.