De clutter everywhere as much as possible , rent a storage unit or family garage away from your property and store it there , depersonalise the property as much as possible
I personally don't like loads of photos / pictures up as it is distracting and Viewers want to visualise it as potentially their home not yours also Stuff on the walls optically can tend to reduce the sizes of the rooms ,.
have the minimum of " stuff " your going to be packing as soon as you sell so make a start now . The clearer the room the better ,
then clean everywhere very throughly including carpets , even if they are replaced by the next owner a dirty carpet will detract from the look you need to achieve .
Mow any grass regularly - at least once a week , trim shrubs & trees, sweep hard standing / hard landscape areas regularly , paint and repair etc where needed , keep on top of the whole property so everything is always ready ,
have all bathroom junk hidden away / removed just a couple of nice towels out , keep the loo seat down for neatness ,
make sure the house is well aired and avoid strong cooking smells / pet/ chemical smells
Make sure everywhere is tidy and beds made
Have the kitchen surfaces empty except for the kettle , put away , store, or dispose of all extra kitchen paraphernalia , the clearer it is the bigger it will look .
Get several ( at least 3 or 4) valuations and go with the middle one . As a pp said some bump up the valuation to pull you in only to get you to drop the asking price a couple of weeks later , if you go with a realistic starting figure it will be quicker and less likely you will have to drop
Keep the bins tidy and make sure they are emptied regularly