iDad is absolutely correct when he says that we need some examples of exactly what is giving you trouble. Examples where you can provide both your "before" and your "after" versions would be the most useful. Also, links to examples from other photographers that have the highly saturated look you seek would also be useful.
This is a complicated topic, and unfortunately, I don't have time at the moment to respond fully, but will do so later tonight or tomorrow. In the interim, may I suggest the following: Download two plugins (...they are either free or there is a free demo version), read carefully the description of the one from Power Retouche Pro, and give them a try on your images. While they can be used to excess, both are designed to give more natural highly saturated colors. They are:
http://powerretouche.com/Saturation_plugin_tutorial.htm
and
http://www.mehdiplugins.com/english/hslplus.htm
HTH,
Tom M
PS - Another technique is to work in a wide gamut color space such as ProPhoto (ie, instead of sRGB or AdobeRGB), but that can be tricky, so lets postpone discussion of that for a bit.
PPS - Another way to approach this problem is to understand in excruciating detail exactly what is limiting the degree of color saturation you have been able to achieve. Some of the common causes are limitations imposed by your monitor and/or printer (ie, you can't see the true results of your efforts), errors in setting up a color managed workflow, trying to simultaneously achieve both bright AND highly saturated colors (ie, so one channel, often the red, has many pixels that are maxed out and hence you lose detail), lighting issues, trying to achieve highly saturated colors on a noisy image (the brightest and darkest pixels (which are probably noise) can't get more saturated, so they limit the overall appearance of saturation), etc.