Need some tips for painting for the first time

I said to my mum i would come and help her paint her hall way and sort of wish i didnt bother now lol. I said i would help her as she hasnt got much money and i thought i would give it a go first and if we messed it up she can then pay someone.

I have painted my old bedroom a few times so have a little idea.

I have watched a few clips on the dulux website and understand i start at the top and work my way down.

I understand preparation is the key. I take it i have to sand all the previous white paint down on the stairs poles and the skirting boards. What should i use for this ? Sand paper or i saw some were a liquid i could put on.

I take it i sand down any rough bits on the wall and feel any cracks. Then do i wash the wall with sugar soap before i start to paint? I was going to use the one coat paint. Is this any good ?

The worst problem is the gap/ cracking between the skirting boards and the wall can i use something to fill this gap?

Can i use the same paint i use on the ceiling for the wood?

Thanks for any tips. Any links to any good products would help.

I take it a paint pod is rubbish.

skirting gap you want decorators caulk...

You wont need to sugar-soap the walls (unless nicotine or cooking stained etc.)
Lightly sand wood with 80-100 grade to key the surface or level loose/flaked areas then undercoat followed by gloss or 2 coats of eggshell or satin instead of the U/C & gloss.
Steer clear of one-coat c*** 'it doesnt-do-what-it-says-on-the-tin'
use oil-based for woodwork..
Paint-pod is a gimmick for noobs with money to waste m8