If you google baby shower checklist or something close to that it gives you like a timeline breakdown of what you should have done by what time. It's pretty neat. My friend planned mine but she used it to stay on track. :-) only thing is make sure you don't go crazy on all the decorations and buy stuff just to buy. I had to stop my friend from buying stuff she didn't even know where she was going to place it.
Pick your theme you want and find the invites..get your guest.list....you also need to.find a place to have it....lots.of.cute ideas on pinterest for games and decorating ideas
If no one has offered to host a baby shower for you, ask. If you have a good friend who you can swap hosting a shower for - she does yours, when the time comes you'll do hers - that's good. Or an aunt, or coworker.
And offer to help the hostess in any way at all that you can - baking, planning games, little treats, etc.
Best wishes -