Depends on lots of variables!
Dave Mallett is your man for describing anchoring techniques. He's done some good posts here and/or a good article in RIB International.
I like having a short (~5m) bit of chain on the anchor at all times. I've been caught out on a calm day without the chain attached, you really do want to be prepared, as holding your position and attaching chain to shackles whilst bobbing around is not ideal. I do use a very small anchor for the boat size (for short stops aboard), so I really need the chain to keep it in place.
A couple of tips - keep an old towel handy for laying chain on the deck so it doesn't mark. This can be useful for padding where the warp goes over the tube if you need it. Also, you might like to consider tying off your bow painter to the anchor warp so that your D-ring takes the load, and the warp coming over the bow has no tension on it until you recover the anchor.
Wayne Rodgers has a handy strip of stainless steel in his rubber bow fairlead which helps lifting the anchor warp and chain without damaging the tubes.
We had a spectacular and amusing demo of a RIB anchored with rope only, back in September. In the wind-over tide, it was dragged one way, then blown the other, and did a complete circle of us. Or did we do a complete circle of the other RIB?