When you first start to learn how to play guitar, what you have to do is to find a song you like that is still really easy, if you don't you will get frustrated and quit for a while, and by a while i don't mean a day or week, it can be a month to a year before you pick up the guitar again. So learn an eay riff or song that you like, then you get started on the other stuff. Whenever you get frustrated with that, just go back and play that riff you like so much and get your spirit back.
Acoustic- When i first started to learn i learned regular chords. So i learned  chords until my fingers hurt then i would try again later, then slowly i picked up a few more riffs and a few more chords, and eventually i go better and better.
Electric- The first thing i did was learned an awesome riff that was easy. Same method as before, but this time didn't learn chords. i learned special techniques such as hammer-ons and pull-offs. I also learned power chords, (they sounded whimpy on the acoustic so i never bothered before). 
 Then i picked up all those skills i needed, a few others i didnt mention is palm muting, sliding, alternate picking along with finger picking(which i'm still bad at), and now i can play whatever song i want with the skills i have so just learn the little things, then you can achieve with the bigs things.  
 
Easy songs for electric:

• Dammit by Blink 182
• Seven Nation Army by White Stripes
• Brain Stew by Green Day
• Sunshine for your Love by Cream
• Iron Man by Black Sabbath

Easy Songs for Acousitc:

• Day Tripper by The Beatles (electric also)
• Bottom of a Bottle by Smile Empty Soul
• Good Ridance by Green Day

 These are just the songs i can think of tell me if i need to add some
Also this is just a suggested way, the way i did it, but that doesnt mean you have to. The only thing that you must do is to practice. That is the only sure way to get better.