So as some of you might know, I'm a member of a marxist party, maybe one of the biggest of Western Europe currently.
The party is not ML. It takes part in electoral politics, though its main focus is building class consciousness at the work places and in the local communities. Getting into parliament is beneficial because 1) money and 2) raising awareness.
The party gets criticized by groups on the margin. They sometimes specifically criticize the MLs in our party for joining, because we are not part of what Lenin described as a Vanguard Party. I guess they are not entirely wrong, I'm not going to call my party ML even though there is (increasing) room for ML sentiment.
My problem is, I don't really know what to do with these critics. Leaving the current party, with tens of thousands of active members and actual political influence, for a 'true ML party' with several dozen people who struggle to organize a book club, does not sound like the way to go. Stop calling myself a ML? That would seem weird as well.
Lenin was not a member of a purely vanguard Marxist party either; the RSDLP contained genuinely vanguardist elements, but also thoroughly reformist ones that agitated for better labor conditions but downplayed and even abandoned their struggle against the repressive Tsarist state (i.e. "Legal Marxism"). Organizations such as DSA in the States and Die Linke in Germany are similarly "Legal Socialist" or "Legal Social-Democratic" parties; unlike pure reformist parties (SPD, British Labour) they openly criticize capitalism, but are afraid to openly challenge the liberal constitutional order for (admittedly valid) fears of being criminalized. But there are elements that are worth engaging with, just as Lenin did. There is no shame in splitting to protect the revolutionary faction from revisionists/liberals, but it's also not ideal.
I would suggest to engage in the party's associated organizations (youth orgs, student orgs). Look for what interests you, whether it is community/labor organizing, direct action, education, mutual aid, electoral campaigns, or even just showing up at a variety of the above and volunteering/baking cookies or something. If the party's organizations have an open political culture, there are bound to be activists you have affinity for. Develop your politics with those comrades, participate in readings/campaigns with your circle, and maybe evolve into a revolutionary faction. Only by demonstrating that the revolutionaries of the party are more capable of leading the proletariat than reformists can Marxist-Leninists in a left party gain hegemony over the broader social-democratic movement.