I think if you are asking this question you are doing it wrong.
I do 'generous' things like that for women quite often, pay for things, offer to help out with stuff, walk them home, help them move things in their houses and whatever. I've never had a negative reaction or be accused of being sexist.
It depends on the circumstances and context, if you then behave in a way that reveals your intentions were to get her to feel she owed you something ("I bought you dinner and paid for all the drinks and still you didn't want to go on a second date? **** you then!") then she will be annoyed. Also if it looks like it's patronising or false flattery it won't go down well. On the paying for things, generally if I asked a girl out then I don't mind paying but if she offers to pay half or says OK lets go again and I'll pay next time, I won't argue I will allow that. If I was going out with a girl that I knew had less money than me (eg a student doing her Masters who was struggling to cover living costs and fees) then I would say look its ok I'm in full time work let me cover paying for stuff, but if it was a girl with a similar level job to me I wouldn't.
If I'm walking up the stairs in a train station and a woman has a big case and is struggling to lift it up I'll say "hey there, would you like some help with that?" and usually they say yes and I'll carry the case up and make a bit of friendly chat and then wish them a nice day, they are always cool with it. I think if you do that and then try and use it as a lead in to one of those pick-up things going "so hey how about give me your number" then it changes the vibe and she will think it was done for manipulative purposes.
I know some guys on TSR like to make out that you can't do stuff like this for a woman without being accused of being sexist, but that doesn't happen in the real world, I think what's happening there is those guys are doing it in a way that is sexist, or are doing otherwise sexist things.
It's a general point I have about those on here that say you can't do anything without being accused of being sexist....I wonder how I manage to go through life doing generous things to women, chatting to them, forming friendships, relationships, dating and so on and never get accused of being sexist...? The world is not some anti-male conspiracy out to get you.