I'm still an anal newbie, but we tried for so long and I tried so many different "tips" given here on LPSG that didn't work before finding a method that did work, that I thought I would pass on what we learned.
I have to stretch my ass out first in order to enjoy it. Mindset isn't enough for me. If I don't stretch out my ass before we put his cock inside me, then it just hurts or feels very uncomfortable. And it doesn't feel better if he continues to fuck me. Your ass may be larger or sized better for the size of your partner's cock. If it isn't, then read on!
I didn't get to the point where I totally enjoy anal sex with TheBF until I first began dilating my ass using dildos of increasing size and length. I originally thought that only my anal sphincter was the issue, but I would feel pain deep inside and that didn't stop happening until I added a longer dildo that stretched me out deeper inside.
Anal plugs didn't work for me. First of all, they don't stretch out my anus and they were uncomfortable. Material also matters. One of my first mistakes was buying a very hard silicone dildo for my ass. I thought that the fact that it was silicone would be better since I could sterilize it, but it was so hard that when I tried using it for dilation, it made my ass too sore to enjoy anal sex, which defeats the purpose! I really like the clear jelly dildos for stretching out. They are squishier than an actual penis and make dilation much nicer. I would never use glass or metal to dilate my ass. I have used a rubber inflatable dildo for anal dilation, but it mainly dilated in girth and nearer the head or the mid-shaft of the dildo, not increasing much in size at the base because my anus was squeezing the air out of the dildo there, so it didn't function well for loosening both my anus and the inside of my ass at the same time.
The next thing is method. I read about this method here on LPSG from another poster, a big dicked gay man who wrote about how he introduces new partners to his cock and who gave the best anal sex advice I've ever read on LPSG, whose name I do not know, so I cannot credit him, but it really worked so amazingly well that I'll pass it on to you.
1. Position: He suggested that on one's stomach works best, and this is what we do when he's using his cock. I lie on my back when I'm inserting a dildo. He mentioned that a lot of people think it's easier for the newbie to sit down on the cock or do it doggy style, but he said that neither position works as well. Sitting down on his cock tenses the muscles in the ass which makes it more painful. Lying down on one's stomach allows the newbie to totally remain relaxed. He said that the only control that the bottom needs is communication, saying "stop" or "more" and the top should listen. I totally agree with him.
2. Dilation method: This is what works for me! He said to insert dildo/cock until you feel resistance or discomfort, then hold it still there for a full minute, and then remove it for a full minute. Yes, it seems slow, but it doesn't go as slow as you would think, especially if your partner is kissing you and touching you and talking sweetly to you, and if you're doing it alone beforehand, then you don't have to go through this whole process right before sex. For some reason, it doesn't work for me without the full minute held still AND the full minute where he takes it out to let my ass rest. When I insert the dildo/cock again, it goes in further than before with no discomfort, like it was meant to be there! The person who gave this tip wrote that removing his cock completely for a full minute is essential for relaxing the bottom's ass muscles, and he is right. I had read advice before that said that the top should keep thrusting slowly to "loosen" me and that it would feel better eventually (it didn't, it just kept hurting or feeling uncomfortable) and that you have to "keep it in" in order to get full relation, but that never happened either. Those tips all failed for me. Anal sex didn't work for me and it was never enjoyable for me until this one guy suggested that the right way to introduce a new partner to a large cock was to allow the ass to relax around the cock/dildo for a minute, then rest for a minute without anything inside it. I took his advice a little further and start off with smaller dildos before moving up to TheBF's cock, but I'm still somewhat of an anal newbie, having only truly succeeded at anal sex with him 3 months ago. I no longer have to start off using my smallest dildo, which I graduated from very soon after we started, and I probably can stop using the next bigger one soon, too, but I sort of like it. It slips in with ease and only takes a minute to adjust to, and I feel like it's a good "starter" size dildo for me.