If your level of representation at national level is a single vote every few years, then the average adult is going to get perhaps 10-20 chances to express an opinion at that level in their entire lives. Western governments probably have more departments than that at any given time.

In any party political system, where your choices even when you do get to express an opinion are limited to perhaps half a dozen candidates and only 1-3 with any real chance of winning, the amount of real information you can convey to government about your preferences through voting in national elections is minuscule.

Consequently, as we see in practice, national elections are mostly dominated by a very small number of very high profile issues, and people vote for the candidate or party that most closely matches their views on their top priorities. One of these is almost always the economy. There might be another that is the political hot potato of the day, perhaps immigration or trade union relations or the fate of some popular public service.

On top of this, once a representative has been elected, in many cases they can then hold office for a full term regardless of their future actions, even if they deviate dramatically from what they said to get elected in the first place.

In this sense, our current forms of representative democracy typically are broken, because there is very little one can do as a citizen to express a nuanced view. Often you will get a choice of least-of-evils from your own perspective and that's it for another 4-6 years.

In order to overcome this, there are a few different things that I imagine would help, but they would all need fundamental changes to existing political systems.

Firstly, an elected representative could have reason to fear being unelected again if they lose the support of their electorate for too long. There is a balance to be found between protecting representatives who take decisions that are unpopular in the short term but genuinely in the long term interests of their electorate and forcing out a representative who says one thing before the election but then does another or takes an unexpected and unwelcome position on some particular issue after they've entered office. However, no politician would ever feel so safe in their position that they could do whatever they wanted without care for any consequences to their own career and influence for several more years.

Secondly, the electorate could have a mechanism to impose its will on specific issues in isolation. For example, if memory serves, a few places do have a binding referendum mechanism where the administration of the day cannot overrule the will of the people once confirmed by a referendum. Again this would presumably have to be used in moderation to be effective, but it would allow the people to express views on, say, environmental and energy policies, or the legalisation or otherwise of recreational drugs, or the legitimacy or otherwise of security measures that infringe on other freedoms. Perhaps the most valuable role of this kind of mechanism would be to highlight a subject that isn't quite a top priority in national elections, and thus to drive greater public awareness of the underlying issue and to promote associated debate.

Thirdly, a written constitution and a strong constitutional court could provide another way to mitigate opportunist or short-termist legislation that would other infringe on basic principles. Like the other two measures, this ultimately comes down to forcing an administration that wants to move the goalposts a long way to achieve and retain the positive support of a large proportion of the electorate on that specific issue for a significant period of time before the changes can become established in law. Of course, as we have seen in various countries, this can work well or not well depending on the effectiveness and independence of the constitutional court, so any such measures need adequate safeguards to ensure as much impartiality as possible.