I’m very curious to begin experimenting with anal sex with my partner, I know he’d love to as he’s mentioned it quite a lot.
However, my partner is quite large 
so I am slightly nervous. We previously tried and it just wasn’t happening but I’m not sure if me being nervous hindered that.
Do any of you have any tips for beginners. E.g. positions, steps to try first etc
You need to start small with beginners butt plugs or dildos and plenty of anal lubricant. It’s thicker than normal lube.
Butt plugs usually have a gentle taper which will open you up slowly and, if you choose one with a narrow waist, they will stay in while you move about.
Dildos feel more like a real penis so you can experience with the thrusting motion once you’ve got it in there.
Start with something about 1" to 1 1/4" diameter and, when you can insert that easily and are comfortable with the size then move to bigger toys in 1/2" increments until you’re using toys around the same size as your partner.
Use them every couple of days (or daily if you’re not sore) until you’re ready for the real thing.
As regards positions it’s really whatever you feel comfortable with. I would suggest that you start with cowgirl though as, with you on top, you can control the speed and depth of the penetration and thrusting.
Hi - great question.
First of all. Well done and congratulations to your partner 
I’ve tried many different anal toys from plugs to beads and I have to say, everything in moderation and plenty of lube.
Start small and work up. I’d recommend a small butt plug to begin with. They don’t look frightening and are actually quite easy to use. There are plenty on LH that have great reviews.
Always get the correct lube for anal and again, it’s really easy to find a good one for anal penetration.
When it comes to positions, I’m not sure and I think it’s down to personal preference. You will need to think of what is best for you. What is most comfortable etc. The common sense approach, I guess, is doggystyle but it’s best to speak to your partner and discuss the best way forward.
I hope this helps in some way - let us know how you get on 
Great advice already given, start slow, plenty of lube. You need to in control of speed and depth of penetration, you could start on a spooning or doggy style position, but with you backing on to your partners erection. Cowgirl is another option.
Great advice above on both how to get used to the feeling and, I absolutely agree with @DLJL on the best positions to start with, so that you are in control. I did, however, want to address this bit:
Yes, yes it does! For PIV, I can, on occassion, not really be in the mood but a bit of foreplay and clit attention and I’m definitely all good. Anal, on the other hand, I have to be really turned on and wanting it, otherwise nothing is going in.
If my head is in the right place, a brief moment of, “Ooh” with first penetration and a minute or two later he can be pounding full strength and really going for it (which he can’t PIV because my cervix doesn’t like it!) and it’s fantastic. If my head isn’t in the right place though, nope, too ouchie on entry. My state of mind makes a huge difference to my enjoyment of anal.
You’ve got to be relaxed and horny, which first go, can be tricky. If you’re not feeling it when you first try, maybe get him to give you a lubey back massage with perhaps a penetrating finger after a bit. Hopefully, that will get you into the right headspace to relax and enjoy it.
@Loobylou12 as others say - use butt plugs on a regular basis - this helps a lot and you will thank yourself when it comes to taking him (but you need to start small and work up to his girth)
Absolutely.
Firstly it’s important to relax and get comfortable doing foreplay or I find a massage always works well with some teasing around your anus to get you comfortable with contact in that area
communication is everything you have to know you’re in control and can pause or stop it anytime and let your OH know how you’re feeling. If you want more / less etc.
Warm up! Fingers. / small toys etc are essential. Start small build up it may even take multiple
Sessions before you’re ready for 
Probably the most important step. Lube! And good lube. I prefer water based but whatever floats your boat. Get a good one too none of the cheap stuff and ideally nothing that numbs. While it may seem like a good idea will only hurt you in the long run as you may not feel tears or push to far too early.
Lube!
If you think you have enough lube you’re not even close.
If you think you have too much lube. You’re halfway there.
Have fun and WANT it to happen. Watch videos or dirty talk to get you in the mood.
LUBE LUBE LUBE
Oh make sure you use some lube.
Have fun
Great advice here so far.
My thoughts would be the following:
Start with small butt plugs and gradually work up in size.
Before inserting a plug, use the tip to tease around the outside. There are loads of nerve ending around the anus, I’d recommend getting used to / enjoying the area externally before trying to insert anything
Always use lube! And reapply regularly. It doesn’t have to be an anal lube if you don’t like them, just use lots and reapply if it starts to dry out.
Combine anal play with clitoral stimulation because this will help you to feel more pleasure and relax a bit more.
Being relaxed is really important. I find porn helpful to really get me excited.
When you come to insert anything, go very slowly, allow your body to relax and adjust to the sensation before going a bit further. If anything hurts or feels uncomfortable stop and try again another day.
I find it easier to insert something if I push outwards, almost as if you are trying to go for a poo, because this will open the sphincter muscles. (Sorry if thats tmi!)
Make sure you’ve been to the loo before playing to avoid mess.
If it doesn’t feel great, don’t give up, just try again another day. Sometimes I find anal feels good one day and the next is just feels uncomfortable for no reason, it’s just random!
Remember that toys are generally more solid than a penis so you don’t really need to be able to use a toy as big as your partner to be able to take his penis, just aim for something slightly smaller.
Good luck and have fun!
There is some great advice here, from some very experienced people, but speaking as a couple who are - how can I put this? - less hardcore, our main tip would be that you don’t have to aim for the jackpot.
I am too large for full penetration, so we settle for just the head of my penis going inside, at most. Besides, when it is too tight, it restricts the flow of blood, eventually deflating even the keenest erection, so it’s like bidding against yourself.
Plus (although they have their fans here), we find butt plugs too clinical, and therefore a bit of a turn-off (even the name puts us off).
There are plenty of other things for you both to enjoy, like using a finger or a tongue, instead of a penis, and (from my viewpoint, as a man), just stroking it against her anus is erotic. Explore all the options.
The good news is although I used to suspect that women often consented to anal play as some kind of favour or concession to their lover/partner/husband, in fact my wife gets a lot of pleasure from it (and therefore me, too), especially since vaginal penetration became virtually impossible after the menopause.
So enjoy!
Feeling nervous can definitely tighten things up and overthinking about it… I’d maybe recommend using the anal backdoor lube to see if it helps or even poppers if it’s something you’d be willing to try out 
Alcohol was helpful in relaxing us both when we were exploring anal sex together. As has already been recommended a good anal lube ( plenty of it) and start small. Plus stop it it hurts. Go slow and tell each other how it’s feeling. As a shared experience it’s so intense and once you are both used to it it becomes so special.