Whether you compete in Judo or BJJ, or both, over time you will come to understand the importance of gripping. Even in NoGi, watch Marcelo Garcia fight for wrist control. He immediately breaks off grips even in NoGi FIRST, before virtually anything else.
At any rate, if you have an understanding of the basics, you can induce a lot of guard pulling and sitting down by virtue of the fact that your opponent feels uncomfortable.
Thus in training, with this, you can dedicate more time to guard passing and gripping to assist your passing than when in preparing for a tournament you prepare for every single position known to man.
As Jimmy Pedro shows in the clip below the basics are:
1) Just b/c you grab your opponent's Gi DOES NOT MEAN he automatically gets to grab yours. He may grab your sleeve or adopt an inferior outside control of the lapel/outside elbow, but you do not simply concede his grips to get yours.
2) Inside elbow/inside control
I posted this on Tuesday to show the basic uchimata to top position to submission. If you watch the video again, you'll see my left elbow flared up to prevent my opponent from grabbing my lapel with his right hand (because that is his lead hand).
As I cross grip (reach with my rear hand to feed his lapel to my lead hand/power grip) you'll notice as we circle he actually grabs my sleeve, and I am forced to break the grip and hunt for his sleeve again. I obtain the sleeve and control it until he stays close enough that I get my high collar/power grip that I've been hunting for.
At that point, he is so far out of position and I have come to control the center of the circle, the uchimata is relatively easy.