I’ve read most of Iain Banks’ fiction, and enjoyed most of it, as I recall.
At one stage, I picked up an Iain M Banks title, and got utterly nowhere with it.
I think I’d like to try again. Where do I start?
Thanks!
Was it Feersum Enjin? 
Try State of the Art, it’s short stories, so you might like to just dip a toe. Failing that, Player of Games is one of the greatest SF works ever written, so start with that. Or the Algebraist, it’s a good standalone.
The question is if you like Science Fiction? (and I realise your username makes this a high probable “Yes”)
I’d second starting with The Player of Games. Most of the M novels are set in the super-cool Culture, so if you’d like some non-spoilery background,here is an essay Banks wrote describing the background.
Feersum Enjin was not great. Interesting but not great. The newest book, The Algebraist, was so so too.
Anything else is recommended, especially those books set in the Culture universe. Start at the start like I did with Consider Phlebas.
I hope I can catch a repeat of the BBC4 interview with the author on the subject (mostly) of his SF works.
The best of Iain M. Banks’ books, if you ask me, is “Use of Weapons” but “Player of Games” is probably a better starting point for Banks’ SF. Fearsumm Enjinn is written entirely in a made-up dialect, so unless you like that sort of thing, you won’t like Fearsumm Enjinn.