I would agree with suggesting Dalloway before To The Lighthouse, because I think Dalloway is generally more concrete and attainable. To The Lighthouse takes Woolf's characteristic stream-of-consciousness interiority a step further and can also be very roundabout in its approach to the "thing" that a character is actually thinking about or trying to say. It's also a bit more experimental in its form, and can be overall a bit harder to "grasp". I think someone new to Woolf would benefit from having Dalloway as an opportunity not only to get used to her style of writing, which will help smooth the learning curve if you decide to read To The Lighthouse, but also to form a judgement of her in a more "typical" setting so that you can decide if she merits your working through her more experimental works. Cheers.
That is also of course a great novel but Mrs Dalloway was the thing that really made me realise how special she was as a writer, so that's what I would personally recommend. It may be that had such an impact on me because I read it before To the Lighthouse and if I read them in the opposite order perhaps I would feel differently.
