Start a political party.
Oh don’t be silly.
Where are you going to get anything like enough funding and support? It takes decades.
See, that’s the interesting thing about the SNP.
Even a decade ago, the idea that the SNP would look like it does today was faintly ridiculous. What they have done is grow from the ground up. It can be done. They haven’t become popular because Alex Salmond is a popular messiah, or because the logo’s amazing.
Its because the party, and importantly its leadership, is made up of people who are largely representative of the population of Scotland – men, women, younger, older, born here, not born here, wealthy, not wealthy, from comfortable backgrounds, from disadvantaged backgrounds – people who aren’t entirely dissimilar from the people who go to the ballot box. The mainstream political parties at Westminster haven’t been able to say that for a long time, and that’s one of the root causes of the UK’s current political malaise, and the often vicious tone of political commentary.
The people that make up a party is one thing, the policies another. The SNP are far from perfect in my eyes, but they have led an effective and largely popular coalition Scottish government and since then done likewise with a majority at Holyrood, while pursuing a fair amount of progressive and equitable policies and overseeing genuine improvements in a number of areas.
The vested interests that control the direction of the largest parties are never going to give up what they have to genuinely make your life better, It is going to take something that grows from the ground up.
In answer to the OP, I voted SNP for the first time at a GE. My sitting MP was an increasingly prominent Lib Dem, whose voting record I had previously found largely representative of my views and whose level of local engagement was what a good MP’s should be. That all changed in 2010. I clearly wasn’t the only East Dunbartonite to feel that way.