Depends on the game you are playing and who you are playing. If your opponent can regularly make bank and kick shots [and pocket their ball], then leaving them with a bank or kick shot will not slow them down much.
*Most* of the people I play have trouble with bank and kick shots or know these are low percentage and will not shoot them if they can avoid it. So I get a lot of mileage by leaving them with a bank or kick shot.
In general safeties can buy you time until things change to your advantage. I've seen many games where it looked like the one player was going to easily win, but good safety play by his opponent turned the game around so the other player won.
An easy safety to start with is to just leave the cue ball in a nasty spot. Don't pay attention to where your object ball will go, concentrate only on where the cue ball will go after the shot. Hit your object ball so the cue ball will go in the intended direction. Then use follow, center, or draw along with correct speed to get the cue ball to go to that nasty spot.
In some bar tournaments, they require you "to attempt to pocket your ball with every shot" and safeties are not allowed. Well you have 6 pockets to choose from for your shot! It may be a somewhat easy cut into a corner pocket, but by banking the object ball to another pocket, you will be able to leave the cue ball in a nasty spot whereas with the cut shot, it would leave the cue ball in a good spot for your opponent (should you miss). So if you are not sure you will make the shot or don't want to pocket that ball yet, might be better to play a safety (don't tell them it is a safety of course). Call your shot - say 6 ball back here in the corner, but of course you have no intention of making your ball - your only intention is to leave the cue ball in a nasty spot and buy some time.
Sometimes a stop shot will leave the cue ball in a nasty spot. Or a bit of draw will do the trick.
In general, leave the cue ball on a rail, or leave a long distance shot for your opponent, or better yet is to leave a long distance bank shot with the cue ball hugging the rail.
Advanced is a half ball hit where both the cue ball and object ball come back off the rail the same distance. (When object ball is on or near a rail) Good snookering shot where the object ball will then hide the cue ball from your opponents ball(s). Aim slightly away from edge of object ball. This takes a lot of practice though.
Or shooting with exact speed so cue ball rolls up and freezes to another ball (this can wipe the smile off one of those bank/kick shot artists).
Then the "wall of balls" trick. If there are a bunch of balls, leave the cue ball behind them. Or if 9-ball, shoot the object ball behind them or leave cue ball on one side and object ball on other side.
Or if 9-ball, leave cue ball short rail center diamond and object ball opposite short rail center diamond.
More advanced is to do something constructive with your object ball while at the same time leaving the cue ball in a nasty spot. Maybe send the cue ball down table to break out a cluster and in the same shot leave the cue ball in a nasty spot. Or move object ball to a better location (I call it my "anywhere but there" shot. The object ball will be in a better location if it is moved *anywhere* else).
Then with 8-ball, there is a "shot-safety". You may have a choice of shots, but not sure you will make any of them. So shoot a shot that if you make it, it will leave you in good position for another shot, but will also leave the cue ball in a nasty spot for your opponent should you miss.
If your opponent is down to just the 8 and you have several balls left, you can even call a safety (BCA rules), shoot in one of your balls with a stop shot (leaving an impossible shot for your opponent due to other ball(s) blocking the 8), and probably get ball-in-hand for your next shot or force your opponent to break out the 8 if it is clustered.
A mistake I made when I first started playing safeties is I would leave the cue ball in a nasty spot for some of my opponents balls (8-ball), but I would not see that he would have a shot on another ball from that location. So before leaving the cue ball in a spot, might want to pretend the cue ball is there and that you are your opponent, then see if you have a shot anywhere. Then if that is a good spot, leave the cue ball there.