Hey guys.

I know a few songs on guitar, riffs and chords etc.

I generally need advice on playing guitar, because I don't know where to go next..

I heard that it's good for beginners guitarists to learn things in a few keys, so that you're generally better all-round.

I know some songs and a few scales up and down the neck. I don't know where to go next to progress and get better..

Please help!
What kind of songs? Difficulty level? Which scales, and do you know them as patterns or by knowing the invidual notes, or both? Also what kind of techniques do you know?

And what kind of music do you want to play in the future?
I can play Day Tripper by Beatles, Superstition by Stevie Wonder, Diamond Hoo Ha Man by Supergrass, Layla by Eric Clapton.

I know the scales by patterns, I don't know the names of individual notes on the fretboard..
And I don't really know what they're called.. There's a bluesy scale around the 2nd/3rd fret that I know.. And one that includes playing 9th and 6th frets on e string, then after a couple strings, 9th and 7th fret, and back to 6th on E string.

I'm still not great with alternate picking, but I'm trying. And I can do hammer-ons, pull-offs, etc.

And In the future I'd like to play all sorts, some really heavy metal stuff like Cradle of Filth, Machine Head, Megadeth, and some softer stuff like Muse, Red Hot Chili Peppers.
Repertoire-wise, I would recommend trying some of metallica's black album stuff, most of the songs in there are very easy and it will teach you the basics of playing metal (palm muting, simple pentatonic solos etc.)

As for scales, read around on the forums on scale theory and then start by learning something simple like a Gminor pentatonic, which you can easily jam over to Smoke on the Water. Don't try to digest the entire scale across the fretboard in one go, instead pick a position and just noodle around on the notes in that position over a backing track and the notes will come to you naturally over time.