Every single person who speaks out in favor of LGBT rights is doing something valuable. Anything that you can do to help is valuable. Support a friend of yours who is queer. Give money to legitimate and effective queer charities. Support social media campaigns that are in favor of queer rights. If you are able to do any of these things, than you have already done more than a lot of other people have throughout history and you should keep on moving forward.
You cannot solve all of the prejudice against LGBT people on your own. No one can. The culture already has changed in the last thirty years, even though it is not where it should be today. We can make it change again.
If you can find a way to be a positive voice in the world, you will help. Thirty years ago, the people who actively spoke in favor of the rights of LGBT people were comparatively rare. Today, this has become common enough that allies are educated on how they can be better allies.
LGBT people and allies are encouraged to try to be positive voices in the world in whatever way will work for them. Some people cannot give money because of their economic circumstances. Some people are too afraid to protest in public because of concerns for their safety as a result of anxiety disorders or past traumas. Some people might have a hard time supporting Internet campaigns because of their negative experiences with Internet trolls. Some people might have a problem with all of the above.
If you are a person who does not tell homophobic jokes and who calls out the people who do, you are being a positive voice in the world. If you support someone who is LGBT, you are being a positive voice in the world. This is how the culture changes. It does not change overnight. It does not change as a result of anything dramatic. A lot of people collectively being positive and working together and refusing to perpetuate bad ideas leads to the cultural change that makes everyone’s lives better.