Quoting -Kaysay-:" Keep up with your Kegels EVERY day and your pelvic floor will get stronger. It's just like any other ... [snip!] ... the muscles you need to target. If you do it every day for an hour or so, you will definitely start seeing a difference soon."
Pretty much this.
Try using only one, if you cannot handle two. You can keep the silicone ones in for a maximum of 8 hours. Make sure you clean them properly. **Using proper cleaning methods**
The Gold Plated weight ones are more fickle. These, if cleaned not properly can tarnish and cause a painful reaction within.
Try to do your kegels when peeing. Pee for a bit, stop count to five pee - and continue till your done.
Do it while you sit.
They are annoying, but can be amazing once you really get into it.
There are other balls like Fun Balls by FunFactory that are joined and have inner balls for sensation etc. Those are fun, but only recommended after sex. They are super painful when your tissues relax.
ANYTHING WITH STRING exposed isn't good... It cannot be cleaned properly (those go for balls that are joined together).
It is not recommended to keep them in during sex, however if it isn't to hard etc it's fine.
It can cause some damage if you're not truly paying attention in the moment...