As mentioned on the Gear page, technique is way more important than gear. Good technique and an average guitar will give you a good sound; with a good guitar you'll have a very good sound.
I get so many remarks and questions about good tone that I think it’s time for some more advice.
I’d say tone is about 80% technique and 20% gear; for the very best tone, you need the best gear, but with most gear that is not crap you can still get pretty good tone if you have a good technique. Also, knowing the fretboard, being able to play all positions with equal ease also allows you to use the 'best part' of the guitar the most. And, obviously, the best gear does not help at all if you don’t have the technique to match. Personally, I like round and clear tone, and a legato playing style, that brings out the tone to the max. MInd you, plenty of great jazz players have a rather staccato playing style, which can also sound great, it's just not my way of playing.
If you are looking to get that sound here are some tips:
- practice slow, let notes ring and feel and really listen for the best tone. Practicing slow and long notes will help you connect the right sound in your mind with the right feeling in your fingers. Everything matters, so really play slow to find out what every aspect does with the sound (such as the spot where you pick, force/not too much, pick/not too thin, left fingers at right angles with neck, pressure on the fretboard, etc.).
- Economize motion and effort; don’t press harder than necessary, don’t pick harder than necessary, make small motions, don’t move fingers that do not need to be moved, and not until they need to be moved. Don’t lift fingers that can stay down etc. Economical motion is better under control than exaggerated and pointless motion, and allows cleaner playing. Your left hand should not be hopping over the fretboard like a kangeroo, but rather crawling like a spider.
- Don’t rush your playing, take as much time for each note as the music allows; often it allows more than you think it does. You can play very ‘late’ and still sound ‘on time’ especially in jazz. It will also help to sound relaxed and natural in your timing and phrasing. Playing too early sounds terrible, even with the best tone. Timing is paramount.
- Then, when you can achieve a good tone, allow it to be heard; play phrases that gives your sound some space, use spaces and long notes besides the shorter and faster ones, don’t crowd them. A good painting looks best if surrounded by empty space, leave plenty of space. Let the music breathe, don't choke it.
- Use dynamics, not everything with the same loudness.
- A subtle, hardly noticable slow vibrato can bring some extra life to your notes, but use it sparingly (except for special effect).
- Be prepared to put in the time to practice; the reward will be that everything you play sounds better. If time is money, spend more time (on practice) than money (on gear)! Don’t waste all your time finding the perfect guitar or amp, practice in stead. Too many players have tons of stuff, but no technique. Having said that, if a nice guitar makes you practice more, then go for it! In any case, as long as you are not satisfed with your tone, spend some time each day, like 30 min, to play plain scales, slowly, making sure you're placing your fingers right, your picking is not too hard, or too soft, and keep listening, until you hear what you want to hear, and be critical. Recording yourself and listening back is also a great way to be self-critical and to hear what needs to be improved. But, it's best to listen (again) some time after recording, preferably the next day, so that you'll listen more as an objective listener, in stead of the person who was just struggling to play and record it, remembering your mistakes.
I know this is all easier said than done, but it does not require magic, just practice, close attention to sound, and some patience.
As always, there are always exceptions; some jazz great guitar players had/have a technique that looks awkward and inefficient. The great Wes Montgomery played with his thumb, which is definitely not an easy way to play, yet it defined part of his sound. But, probably no guitarist ever approached his ability with that technique, so, it was great, but unless you also have a magic thumb, I wouldn't recommend playing like that, at least not as you primary technique.
Phrasing: this is another interesting and often debated topic.
For me, phrasing should find a balance between variation, surprise and coherence, and I guess it's best to start with the latter. When you start trying to build a solo, start with some basic ideas and just vary, find other ways to play a couple of notes, that way you will learn to discover more possibilities. It seems trivial, but that's the basic thing. When you get more comfortable with this, try to avoid the obvious: don't always start and end and on the same beat, don't play in 'blocks', i.e. all equal length phrases, don't always start or end on root notes etc. Anyway, my exercises package has lots of examples of this.
Something that I see when looking at my own solos in notation: the phrases/lines go up and down like a sort of gradual wave: from high notes working down to low notes, then moving up again in an almost periodic fashion. Moving from high to low and vice versa provides variation in sound, it just feels natural and flowing. Playing in the same register too long gets boring, so you have to learn to use the whole fretboard!