The best way to help with correct spellings is to get her reading and writing.
Ways to do this:
Read to her every single night from a story book she loves. Get her to read a page out loud to you and then carry on, or you start, then stop at an exciting moment, get her to read the next bit. I used loads of tricks like: my throat is dry or I'm too excited to read on - you do it, so they didn't suss it was homework.
Let her see you reading. Buy Sunday papers and buy her a magazine, comic or children's newspaper. Make lovely cool drinks of juice and soda or chocolate milk or whatebver, find a cool and shady place and read side by side for 15-20 mins.
If she seems interested in something - animals or science or ballet – anything – buy her some simple books on the subject, with some illustrations but plenty of text too.
Always pick up a copy of the Metro for her on train journeys and have a contest to see who can find the silliest or cutest story.
Make a special dinner and ask her type up a "Menu' on yoru laptop, and then help her correct the spellings. Never cirticise poor spelling just say, Ah, great, sketi! Did you know it's actually spelled spaghetti? So many letters but that's how they spell it on menus and this is a menu!
Get her to read labels on things when you go out shopping or read the aisle signs to find where things are.