It partly depends what the wall material is. If you're lucky, you might find where you want to screw into hits one of the wooden frames that sometimes hold together internal walls. Screwing into wood is easy.
If the wall is concrete, plaster on thin wooden strips or brick, you'll need a raw plug. Most internal walls are plaster, most external walls are concrete or brick. Concrete or brick you'll need a special masonry drill bit and a drill with masonry action (hammering).
Pick a raw plug that seems slightly smaller than the screw or even smaller than that for the nail you want to insert. Pick a drill bit that is just larger than the nail/screw. If unsure, drill with a bit that seems too small to start, and then redrill with a larger bit if it really is too small. Having drilled the hole (straight as you can), fit raw plug, it should go all the way in. The nail or screw should hammer/screw in tightly.
Sometimes (plaster walls) you have to pack the hole with 2 raw plugs (one inside the other) to get a snug fit.
If the wall is concrete, plaster on thin wooden strips or brick, you'll need a raw plug. Most internal walls are plaster, most external walls are concrete or brick. Concrete or brick you'll need a special masonry drill bit and a drill with masonry action (hammering).
Pick a raw plug that seems slightly smaller than the screw or even smaller than that for the nail you want to insert. Pick a drill bit that is just larger than the nail/screw. If unsure, drill with a bit that seems too small to start, and then redrill with a larger bit if it really is too small. Having drilled the hole (straight as you can), fit raw plug, it should go all the way in. The nail or screw should hammer/screw in tightly.
Sometimes (plaster walls) you have to pack the hole with 2 raw plugs (one inside the other) to get a snug fit.