I have had a glass bottleneck for years, and I couldn't play a lick with it.
Then I bought a dobro because I fell in love with its sound, and I thought that I should play some slide licks on it... But I tried with a metal one, and this time, it worked from day one. I've heard stories but in the other order...

So try different types, they are as important as strings gauges and picks. Pick up a few licks and tunings on this site too... Then work from there.