What tips and techniques do you guys use to spice up you Blues playing?

Bends are always a must. There are actually notes which sound best bent, at least (generally) fit better when bent, but unfortunatly I couldn't help as I never lernt which notes they were, I just went for any...
I was playing a 12 bar blues with my dad on rhythm guitar, and suddenly I broke out of the pentatonic scale into a Phrygrain Dominated (Spansh scale), which had some pretty wild affects. Try borrowing notes, or a run of notes, from other scales if you don't want to go into a whole new scale, see what happens. The key is, as with everything, to experiment, try new things; as the saying goes "Don't practise what you know, practise what you DON'T know!"...I've found it's the quickest way to learn.
There's a tonne of other things you can do to spice up your playing, but I'm afraid that's my two pence worth. Hope it helped, good luck!
While I remember though, think about taping yourself or recording your playing on your computer, ask people what they think, the majority of people at the forum with gladly give you constructive critism or praise. Okay, now I'm done...

Sometimes it can be nice to add a 9th to the blues scale, I think SRV uses that quite often....

The blues, its all about getting in touch with your emotions, its not just about a few bends and trills here and there, its all about whats going on inside of you. Alot of musicians have trouble hgetting in touch with their true emotions through the blues (without sounding like someone else), but you just have to know how to take a few key elements from the work of others without losing your own sence of creativity..Listen to Jimmy Page, his playing style is unbelievable. The thing with the blues is that alot of people feel that they can't relate to it, But with Page's style, he adds so much flavor to to the blues, and so much enthusiasm for the listeners as well. Jimmy Page's style has remained one of the most unique styles over the past four decades, because he polayed from the heart, discarding what was considered acceptable at the time.

-Joseph, :).

Try using the b3 and #5 in a penatonic to make for a nice blues sounding scale.

As for bending, lets spell out a c major pentonic

C D E G A we find the 1 2 3 5 and 6

add the blue note to get the blues scale
C D Eb E G A the flatted 3rd or 1 2 b3 3 5 6

Turns out that bends on the 5 into the 6 are very appealing to the ear as well as a bend of the 2 into the 6 with a possible stop on the 5 on the way to the 6.

Take this one step further and insert a #5

C D Eb E G G# A all of a sudden you have instant Led Zepplin riffs. Start on the D and play until the A and bend the A like crazy. This pattern is an excellant one for ripping off a ton of notes in a limited area on the neck. This gives you the ability to shread to some degree, but for the sake of blues leaves a lot of options for filler.

Good Luck!

I like Wide's idea. Adding a 9th to the minor blues scale is essentially like mixing the minor and major pentatonic scales.

This 9th sounds really cool with resolutions. Bend up the 3rd, pull off to the 2nd, then to the 9th, and then resolve.