As a beginner, I found it extremely hard to transition chords on time, and correctly. I was great at putting my fingers where they belong, I just wasn't fast enough. I worried about playing the strings that I "wasn't" supposed to.
On certain chords you only play certain strings, quite obviously meaning, don't touch the ones you aren't supposed to play. My approach was, don't bother with that. They're called open chords for a reason so I left them full open. Only when it's the correct way to play a song will we worry about muting certain strings. (But I wont be teaching you that.)
Some chords we can use are:
Em (E Minor): 022000
G: 320033 and/or 320003. For this chord, do whichever one that is easier, they're bother correct. Practice them both eventually though.
Am (A Minor): 002210
Simply practice 2 at a time, as slowly as you need. For example, Down Strum an Em chord 4 times, then switch to a D chord, down strum 4 times, then move back to the G. Repeat.
Do that as slowly as you need until you feel absolutely comfortable with whichever 2 chords you chose. Then take one of your comfortable chords (Lets call them that for now, just me and you guys ;D ) and practice something you haven't practiced yet, until you're comfortable with that.
Do the same with every chord combination you can think of. To speed up the process a bit, do 3 chords instead of just 2. Even 4. I did all the chords I knew at a time, so I went from Em to G, to C, etc
Some more chords you absolutely MUST add to the list, and I'm not going to give you any Add9 chords or anything like that.
A Major: 002220
E Major: 022100
F Major: 003210 or 033210 or 133211 (That 3rd one is a barre chord. Go look at some barre chord lessons, and use my method when you wanna try to switch between an open chord and a barre chord.)
. You probably already know this, but just a reminder: an A chord is an A Major. an Am is an A minor. Same for all other chords. E is E major, Em is E minor.
Another thing you should know. Barre chords are NOT easy at first, at all. It took me 3-4 months just to wanna be able to do barre chords, and that was after 3-4 months of doing open chords only.
Don't let your guitar scare you into quitting. Everything may look scary at first. Scales, Solo's, Reading Tabs (I picked up on that before playing guitar...), Playing live, Playing for anybody. Once you get the hang of one thing, and you want to feel that satisfaction of being able to do another thing, GO FOR IT. Do not give up when it comes to the guitar, it's not as hard as you think, and that's coming from me, a slow learner.