Should I recite prayers or make up my own or do a combination?
Combination. I'm currently reading Spe Salvi, and Pope Benedict explains it like this (paragraph 34):
For prayer to develop this power of purification [to open us up to God], it must on the one hand be something very personal, an encounter between my intimate self and God, the living God. On the other hand it must be constantly guided and enlightened by the great prayers of the Church and of the saints, by liturgical prayer, in which the Lord teaches us again and again how to pray properly. [...] Praying must always involve this intermingling of public and personal prayer. This is how we can speak to God and how God speaks to us.
The "formulaic" prayers that we memorize are important, in part because they teach us how to pray. Most likely, you'll go through times in your life where you'll feel "dry", and you'll struggle to know what to say to God, struggle to feel his presence. Especially during these times - but during other times as well - these prayers are a real treasure. We can also pray together with the whole Church when we pray these prayers, because many of them are prayers that the whole Church has in common.
But you need to make up your own personal prayers, too. Ultimately, prayer is talking with God, and prayer is about building up a relationship with God. And just like in any relationship, you need to communicate your own personal (unique to you) hopes, fears, sorrows, longings. So you really do need both types of prayer.
What are the most common or popular prayers for you guys (other than the prayers involved in the rosary, of course)?
There are so many out there. A morning offering is a good idea (that can be recited or in your own words). There's the Angelus, which is often prayed at noon each day (and sometimes at 6 am and 6 pm as well). It's also good to get in the habit of doing a brief examination of conscience before bed, followed by an Act of Contrition (again, either recited or in your own words).
How do I achieve meditative prayer?
The rosary is a meditative prayer, so there's that. Personally, I really struggle with the rosary (I tend to get overwhelmed by trying to do so many things all at once: counting with the beads, praying aloud, meditating on the mysteries), but you can also do meditative prayer in other ways: the Divine Mercy Chaplet and Lectio Divina are both meditative prayers, and prayer before icons or before the crucifix can also be meditative.
The Catechism has a good section on expressions of prayer which discusses meditative and contemplative prayer.
How can I study the bible correctly and be able to recall passages as some of you do in the comments?
I can't speak to recollection (I think some of that just comes with time), but a couple of suggestions for Bible study: Probably the easiest way to start is to find a Bible Study at a local parish. It's also a good practice to read from the Bible regularly, ideally with the help of a good study Bible. The Ignatius Catholic Study Bible is good, but it's New Testament only. Other resources might be a Navarre Bible or the Didache Bible (also from Ignatius press).
And finally, how does one properly do the process of Lectio Divina by oneself?
For Lectio Divina, check out [this explanation](np.reddit.com/r/PrayerAcademy/comments/24y6ys/prayer_academy_ways_of_prayer_lectio_divina_18/).