decorating novice - please help

[cansu]

I am going to attempt to do some painting around my rather battered house. I don't have the funds for a decorator so need to do it myself. One of my projects is to repaint the banister as the paint is grimy and worn away in places. I have bought Dulux Satinwood in white cotton, but am now wondering do I need to sand and then put some kind of primer on first?? When I google, some sites talk about stripping off paint completely first and then priming. Some say sand and then prime and some say slap the paint on after cleaning thoroughly. Please advise!

Always sand, wipe down with damp cloth and then paint. If previous paint or varnish is dark then prime after sanding and wiping. Lightly sand if two coats required.

When sanding, as it's curved surfaces use sanding sponges, Jewsons have them about 60p each. You'll need a few.
Satin wood is self priming.
T class brushes are the best value to quality I've found. They do a 5 pack of different sizes about£15 at screwfix

Rather than try and wash out gloss brushes we've taken up buying cheaper brushes, wrapping them very tightly in cling film at the end of one coat so you can use them again, then ditching at the end of the project. This may be breaking decent DIY rules but I REALLY hate washing brushes.

To clean brushes which have gloss paint on, I have a very small mug which is just big enough to hold them. Then I only end up using a small amount of white spirit to soak them in. I usually soak them overnight.

I use cling film for rollers (with emulsion paint on them) and only wash them at the end of the job. It saves so much time :-)