30 songs? How about 3 weeks. That's just a guess. I'm in the same boat, but with a larger selection of songs to learn. Fortunately I know most of the songs well enough to know where they make their changes. My technique is to find them on youtube and play along. In another window find tabs or whatever you can to get you started. Use your ears to find what's really going on. After you've played and learned the different parts, listen to the song again and write out the map (e.g. Intro, Verse, Chorus, V, C, B, C, C, Outro) After that, bookmark the youtube page and go back to it and practice the song as frequently as you can. For some reason, once I've mapped out the song I don't need to read what I wrote and the song seems much less mysterious. Take the songs in memorable chunks, not all at once. When a song continues to give you problems, write notes about it and you'll remember that one especially well.