Putting up coving
There's no real 'correct' place in a room to start putting up a coving, if possible, start with a simple corner where the wall is longer than one length of coving. Leave the fiddley areas around chimney breast until you've got into the swing of it.
If using powder adhesive, mix some in accordance with the instructions - don't mix too much as it will only be usable for 20 to 30 minutes.
Cut the first mitre joint(s), when one end of the coving is to be a straight joint, always check it for damage and trim straight if necessary. On plaster coving dampen the edges which will be fit to the wall and ceiling. Dampen the area of the wall and ceiling (this will help ensure good adhesion).
Evenly spread some adhesive along the top and bottom edges of the coving where it will be in contact with the wall and ceiling.
Position the length of coving along the marked line and with the mitre in the corner. Press the coving into place, gently pressing along the length of the coving to ensure that the adhesive is spread evenly. If the ceiling or wall is not straight, do not push hard where there is a large gap, the moulding will relax reducing adhesion.
When putting up long pieces of coving, it may begin to sag before the adhesive has set. If this happens, insert one or two nails into the wall under the bottom edge of the moulding to temporarily support it - after the adhesive has set, the nails can be removed and the holes filled. It's sometimes necessary to put a couple of nails in the ceiling to stop the moulding 'rolling' forward, again, remove these after the adhesive has set and fill the holes.
Heavy plaster coving may need to be fixed with screws anyway. With the coving held in position without adhesive, carefully drill through the coving at about 1 metre spacing and into the wall. Countersink the holes in the coving, and fit wall plugs. Spread on the adhesive, reposition the coving and secure using brass screws. After the adhesive has set, the brass screw heads can be covered using filler.
Surplus adhesive pushed out of the joint should be scraped off with a pallet knife, use the surplus to fill in any gap visible. Clean off the residue with a damp sponge or cloth.
Continue to cut lengths of coving and put up working around the room carefully lining up each new piece with the adjacent piece.
After the first length goes up, each piece will have at least one joint, be it straight or mitre, put a blob of adhesive on the end so that the lengths are bonded end to end.