It's a common mistake for new guitar students to place too much initial focus on fretting the open chords. Guitar playing is a two handed endeavor and the laws of strumming are not to be ignored... 



The feel of the strum:
New guitarists always strum with their strong hand (righties with the right, lefties with the left). You've probably become accustomed to using your dominant hand for most things - so the responsibility of strumming shouldn't be too daunting. Go with the stronger hand.

Make no mistake, it's important to get this down. It won't matter if you can play 50 chords or slide down the guitar neck ever-so-perfectly, if you can't get your strumming and your basic rhythmic patterns - you've got a big problem.

Keep in mind, its the strum hand that's actually PLAYING while your other hand decides what the color of the sound will be like, (chord types; i.e., Major, Minor, Dominant). You need the strumming hand to learn how to feel rhythm and create a groove. This is why it is so important to develop the fretting hand during those early days of strumming practice.

We'll break down the introduction to strumming and rhythm techniques into two parts: "Wrist Mechanics" and "Exercises"...



Wrist Mechanics...
New students often pick up a guitar and start strumming by using their fore-arm muscles. It's all too common, and it doesn't help them to develop feel.

Turning or rotating the fore-arm over and over isn't a great strumming technique. Students are often left rubbing their arm after playing for 5 minutes. You can't use all arm when strumming, you'll cause too much stress on that rotating forearm muscle and upon those tendons.It will actually start to hurt you.

This is the BIGGEST part of strumming mechanics. And maybe the hardest part to learn. You need to have the strum come from your wrist. Even if you're a punk player Ramones-ing your way through power chords. You need to strum from your wrist, with your arm angle and string tracking coming from your elbow.

The idea of this is you want a fluid wrist motion that really connects on the down strums and produces the right upward "brush" on the up-strums. Remember, that there are more dynamics (loudness) on the down-stroke than on the up. The up-stroke will just clip the strings, attacking only perhaps the top 3-4 strings at most.



Mastering the Down and Up
Down-strums and up-strums are not science, they're instinct, sound and done correctly they are also artful. Down-strums (when you go from the low to the high-strings - down toward the floor) create more impact. They're louder and produce more volume and impact. Up-strums are the exact opposite. They're lighter and offer us less dynamics of sound.

Good guitar players not only use both strum directions, but they know WHEN to use both. You'll want to learn how to integrate the two strums together as well as, separately. The strumming direction offers us a different sound, so sometimes an up-stroke may be too weak. And, for other times, a down-stroke will be much too loud. You'll need to learn their sound difference, how to balance them and when to apply them within a song.

Once you understand and have control over strum direction, you can take that knowledge and never have to worry again about whether to strum down or up. It'll just be natural, because you'll be listening for the impact of the string sound and the sound of the part musically.Through instinct you'll learn to apply the correct strum directions naturally.

Have a look at the Creative Guitar Studio Rhythm Course "Rhythm Guitar Basics" to help get you started on strumming guitar with proper rhythmic meter.



Exercises
Here are a few strums you can practice at home. To start -- you'll want the basic "Down / Up."

Ex. #1). Turn on a metronome or an online drum machine

STRUM in time: Down -- Up -- Down -- Up ...etc.

This is the foundational strum. The exercise helps you practice going down and up without any problems. Use a metronome and make sure you can keep the same pace with both directions. Be sure to use your wrist and keep a slight angle of the pick at the string to offer less resistance across the strum.

After you get the basic down and up, you can move on.

Ex. #2). Turn on a metronome or an online drum machine

STRUM in time: Down -- Down - Up -- Up -- Down -- Up -- Down

Example two is a good concept of how rhythms may feel in songs that you play. It's not going to be as simple as "Down, Up, Down, Up" in every song. You'll need to have more control and more variety when you play up or down for a groove.

Video Lesson:




The mechanical side of this is vital for generating greater strum variety. Through the use of beats, drum machines and a metronome you'll slowly get a better rhythmic  feel for strumming.

Work diligently at it and listen to a lot of different songs. Work hard at copying the strumming used in tunes you are studying. Over the weeks and months ahead, your instincts will get better and you'll start performing strum ideas exactly along side the recordings you enjoy playing to. If you're still having difficulties, join the "Creative Guitar Studio.com" website and study the courses. 

There are several chapters on rhythm and strumming in both the Introductory and Intermediate courses.