Most of the negatives on the "Do women like DP" seem to centre around not liking anal sex or finding it difficult. Interesting to know what all sexes think about this subject. Be serious now.
When I was in my teens and 20s, I wasn't particularly interested in it. Thirty years later, I regret all the missed opportunities ... girls wanted to be technical virgins then and didn't want to get pregnant but they were still HOT (believe it or not!). Unfortunately, my technique was bad. I remember a girlfriend who was really interested it and poked her bum right up in the air, really up, to encourage me. I jammed it in without much thought. Very poor experience for her and not much better for me. Put her right off and also off DP, in which she had expressed an interest previously.
I know more about it now and will repeat what's in the DP thread. My experience is that most people don't really enjoy anal penetration until the sphincter is dialated fully but then tend to enjoy surprisingly deep penetration. As a student, I vividly remember a rather proper middle-aged woman clearly experiencing a powerful orgasm during proctoscopy.
Some people do have very tight anal sphincters and there drugs and surgical procedures to relieve this. I'm not suggesting that for this purpose. You can "train" your sphincter by inserting a progressively wider series of objects. Within reason, object length is no problem since the average large intestine is long. Another tip is to insert the object tip and press firmly towards one of the legs, rather than to just push straight in or pushing fore or aft.
Most sources say that much lubrication is required for anal intercourse although my experience is that a little saliva or pre-ejaculate will do; but better too much than too little, though. You *really, really, really should use a condom* against STDs and a water based lubricant is important (e.g., K-Y) then; petroleum based lubricants will dissolve the rubber in a few minutes. Another reason for using a condom is to deal with the dreaded "brown hat" phenomenon (I've never actually had that happen to me) and for cleanliness in general (you can get urethritis from E. coli or worse being pushed in).
Warnings! Large objects (or excessive enthusiasm) can tear the sphincter or relax it permanently. A tear may have to be repaired surgically and a lazy sphincter can lead to faecal incontinence, both of which are unpleasant and embarrassing. Another warning is about losing dildos and objects in the bowel. We used to laugh ourselves silly in A&E when these patients (always men) attended, but it may require more medical attention than you really want under the circumstances. Also, although the bowel is over a metre long, it makes a sharp turn after the rectum, so don't push in anything too long, especially if you get resistance, and don't be too energetic. A bowel perforation is a life-threatening emergency!
Have fun!