Go on fetlife, there are loads of groups on there about being a domme. Loads of info and advice to be had x

Yes fetlife is great

If you want to start, start of small first i.e tie and tease and spankings or roleplay i.e humiliation, see if you can not find a domina in your area who is prepared to train you, you will also find from time to time that there are Masters and Dungeons out there who offer up training courses in bondage etc.

There is so much you can get into but remember tie and tease is not just limited to a bed but also a chair, you get door restraints etc.

If you are thinking of starting some good advice has been given already, and yes it is physically draining especially when you get 2-3-4 hour sessions, let it flow if you know what you are doing, if not you will find you are just stumbling through the session, a lot of PD's have tried and just think give them a quick whip or stick a strapon on, it's not about that, fantasy and fetish with a great imangination is always key!
My advice don't look at the American Porn Pro DOMME clips, look at British ones or German, get yourself a website done, get on as many fetish sites as possible, and as nia suggested get a lot of equipment, I have spent umpteen thousands and have bespoke furniture, and clearly set your limits, I.e do you do SCAT? Needle play....etc
You get a lot of TW's but there are serious submissives who want the correct session, and will tell you what they want down to the tee, but foremost you are in charge, they listen and act, you are there superior when in your presence, don't ask ' is this ok for you?' Set rules at beginning and if you are doing full on BDSM session set clear the rules and if needed code words at beginning of session, and don't just jump into a full on session straight away, also learn how to spank and whip without leaving marks! That's a good one as some love it but remember they have families and partners, it's an art!
Hope this helps

Thank you all for good advice, they?re very helpful. I?m curious about it, and will start with soft dominance with a client next week.

I don?t know with a Domme, but as someone suggested in this thread, you could also have a Master to train you if you can?t find a Domme, even though it?s not quite the same thing. I will have a Master to train me, he will guide me and then switch for me to practice. Good luck! 

There are some that run "Lessons" or maybe email someone in your area. Are you in or near London?

Im in peterborough, so not too far from london on the train xx

Thats brilliant, thankyou xx