As for Scriptural evidence for Lent, how about Christ's 40 days in the desert, being tempted by the devil, before His Baptism? I've also heard some mention Moses' 40 days fasting on the mountain before God gave him the Law.
I'm an Orthodox Christian and we observe Great Lent (as we call it, or the Great Fast, to differentiate it from the other three fasting seasons of the year) pretty heavy duty.
The triad from Matthew chapter 6 - prayer, fasting, and almsgiving - are the basis of our Lenten disciplines. Christ said "
When you fast..." not "
If."
Our fasting (when we use fast, we really mean limiting the TYPE of food, you're also not supposed to gorge yourself) is of a rigor that seems to astonish and appall many Western Christians. We essentially go vegan for all of Great Lent. We ease into it kind of gradually. The Sunday eight days before Great Lent begins is known as Meatfare Sunday - this was yesterday - the last day to eat meat before Pascha (as we call the Feast of Feasts, Christ's Resurrection). Now for this week is called Cheesefare week, until next Sunday (called Cheesefare Sunday), is a meat fast. We can eat all dairy - milk, cheese, eggs, yogurt - and fish in the Russian tradition, to which my parish belongs - every day this week, even on Wednesday and Friday, on which we fast virtually every week of the year. With the other three fasting seasons and W & F, we fast for about half the year.
Our fasting discpline is no meat, poultry, fish, dairy, eggs, oil (some interpret this as all oil, others just as olive oil - depends on the tradition, whether Greek or Russian, for example), and wine (all alcohol). Shellfish is allowed - some think since it was the food of the poor in the Mediterranean countries where Orthodoxy was prevalent, although it's expensive in many places. I keep it for special occasions (such as my birthday which is during Lent). Fish is allowed on the feast of the Annunciation (March 25) and Palm Sunday. Oil and wine are allowed on weekends, and a few other special saints' days. It's common for people to eat only two meals a day (no breakfast) and to leave the table before becoming full. No in-between meals eating.
Of course, if you are pregnant, nursing, or have other medical issues (such as diabetes), the fast is mitigated for you. But you talk with your spiritual father (usually your parish priest) about how to deal with lessened fasting by other spiritual disciplines. I've known diabetics to only drink water during Lent, since they can't fast as the rest of us can.
Since our liturgical time is counted from sundown to sundown, as in Judaism, our Great Lent will actually begin with the Vespers (evening prayer) service next Sunday evening. We have a rite of forgiveness, where all those present will ask forgiveness of everyone else - the response is "God forgives." Nice way to begin Lent.
There are services several times a week in the evening, in addition to the normal Saturday evening Vespers and Sunday Divine Liturgy. During the first week of Lent, there are services each evening. During Holy Week, there are even more services. One of the most beautiful of the Lenten services is the Liturgy of the Presanctified Gifts (on Wednesdays and Fridays only, and M-W of Holy Week). It's a Communion service with consecrated bread and wine from the previous Sunday combined with Vespers.
Our Lent has the theme of "bright sadness." An excellent short book to read on Orthodox Lent (probably in your library) is
Great Lent: Journey to Pascha by Alexander Schmemann.
From eating more simply during the fast, we save money, which we then give to the poor. It can be done a variety of ways. My parish always has a barrel for canned goods for our local food pantry. You might donate to a homeless shelter, even do some volunteering yourself at a meal for the homeless, or even give $$ or a grocery gift card directly to someone you know in need.
You're also supposed to increase your personal prayer, in addition to attending more services. Confession during Lent is an absolute necessity. The Lenten Prayer of St. Ephrem the Syrian is said daily M-F during Great Lent:
O Lord and Master of my life: take from me the spirit of sloth, faint-heartedness, lust of power and idle talk.
But grant rather the spirit of chastity, humility, patience and love to Thy servant.
Yea, O Lord and King, grant me to see my own errors and not to judge my brother, for blessed art Thou unto ages of ages. Amen.
For some short but good explanations on Orthodox Great Lent, begin here:
http://www.oca.org/OCchapter.asp?SID=2&ID=65 and just click through to the following sections.
Personally, in addition to daily Scripture readings (the Psalms are an especially important part of Scripture to be read during Great Lent), my Sunday morning adult class will be reading a wonderful small book (100 pages)
Way of the Ascetics by Tito Colliander. It's by a 20th Century Orthodox author on applying the ancient ascetical tradition to modern life. For my own reading,
The Ladder of Divine Ascent by St. John Climacus (6th-7th Century). This book is NOT for the newbie! There's some very heavy spiritual stuff in there. This book has been traditional Lenten reading for both monastics (often read aloud) and laity for centuries. I'll also be at every service - Saturday Vespers, Sunday Divine Liturgy, Wednesday Presanctified, and Friday Vespers - but I'm a choir member and this is part of my responsibilities. You simply make your faith and service attendance the number one priority.
I *love* Great Lent.

It's definitely something to be experienced. Yes, the fasting can take a bit getting used to - it's definitely challenging - but the long fast, all of Holy Week, and then the glorious Matins and Divine Liturgy at midnight on Pascha - when you come into the church ablaze with light after the long dark Holy Week and the midnight procession in the dark with candles on Pascha - that first "Christ is Risen! He is Risen, indeed!" exchanged between the priest and the congregation is an experience that I can't describe. It's the most glorious service of the year. Lots of us actually feel a "liturgical letdown" after Pascha. It's weird, but it does happen!
ETA: in addition to our fasting from food, you're supposed to fast from sin, period. But we're human, so we don't stop sinning, but things like gossip, being mean, etc. - things we can control, are definitely on the list of things not to do!
ETA 2!: One of the things I love about Orthodoxy is that the Lenten disciplines have been the same way for *centuries.* There's no deciding what to "give up" because it's already there. I've got Catholic and Protestant friends who just agonize themselves into absolute knots each year over what to give up for Lent. The stress they go through is incredible.