Whether you're starting a new project or are settled into a fully established band, the topic of performing covers enters the rehearsal rooms. Do you play them? If so, what do you play? Do you stick to as close to the original as possible, or do you give your own interpretation to it?
The first cover I worked on with a band was while I was still in Junior High school, and I still remember working on it night after night for weeks in the school's band room after hours with my bandmates. It was "The Final Countdown" by Europe. Between the arguments with the keyboard player "no, that's the BASS line, you stick to the KEYS" and trying to lock in with the drummer during the guitar lead, we could not make that song work if our lives depended on it. As a result, we never performed it. In fact, we never had the opportunity to get on stage because after wearing ourselves thin on each other, we realized we weren't all that great of a fit as a group.
A few years later I got into a project and started to rebuild on my library of covers... Still trying to play it just like the original artists intended, but by that time I was settling into my own playing style, and found trying to be "just like the original" was even more difficult than working with the project in Junior High. So I took a different approach and made it SOUND like the original, but if there was a bass fill I could add in when it was too simplistic for my liking or modify a verse if there was too many noted for my amateur hands to follow - I did it. And it worked. For me at least.
I've worked with musicians who swore they NEVER wanted to play a cover, because they didn't want to be compared to the original artist, and/or felt cover songs are for those who lack true creativity as an artist. I've also worked with folks who wanted to play just covers because the songs bring back great memories for them, and/or their original creations they wrote just for themselves; they had no interest in performing or recording it. So who's the better artist suited for you to work with?
If you get the chance, work with both. Grabbing a tab for the tune you got stuck in your head is one thing, but play it as the artists designed for it to be heard is another. I'm sure everyone who has heard live music has heard that one song and thought "wow, they are destroying this song, my ears hurt!" - Whether it was the singer tried to turn the song into his own, or the collaboration just wasn't a good fit overall, there could be a million reasons why it didn't sound like the original. But in the end, you didn't like it because it wasn't received in the same manner the original artist wanted you to hear it.
But then again, taking a composition and rewriting it to suit your project's sound can be rewarding. I saw a metal band in Dallas perform Katy Perry's "I kissed a girl" and was amazed how they performed it. Without a female vocalist. I also recall a friend in Winnipeg once tell me how part of his band's show was letting requests come from the crowd. If they didn't know it, they still gave it a shot. the secret was, they made it their own and were successful at it, because it wasn't EXACTLY how the original version played.
I remember doing a show a few years ago and we mixed covers and originals, and the crowd loved it. The theory was to attract them with the tunes they know, and keep them attracted with the ones we wrote. At one point in the show we called out to the crowd and let them pick which one of us would start a riff, and the rest of the band would join in. We started with the rhythm guitarist (he actually just let an open A ring out and shrugged, but whatever...) and slowly the other band members joined in. After the show, members of the crowd came to us and said "there's no way you created that song just there and now" - but with the chemistry we had as a group, that was the unwritten rule of the band: first one ready to play, starts a riff, everyone else falls in. Over time, it actually got us some good songs.
I think part of the secret to building on your skills as a musician is simply not limiting yourself to a playing style, genre, or instrument. If you got skills to compose, then build on the compositions by trying instruments you never played before. If you're playing covers, make it your own, but keep it close to the way it was recorded - use the tabs as guides. The only way you'll know if you've given your best to whatever you play, is to approach it with heart and soul, and leave no options uncovered.