I'm a first time traveler and I am planning on traveling to Germany for a week (including travel time) either from late October to mid December (right before Christmas) by myself. My plan is to land in Dusseldorf, go to Cologne, then Bonn and possibly back to Cologne, (where train tickets are cheaper) to finish in Amsterdam before heading back to Dusseldorf. My goal is to do this as cheaply as I can, I am very flexible on when I want to go hence my time frame and going solo as well from October to December at anytime, whenever is cheaper (mostly in terms of airline tickets) or just in general a good time to go.
I don't think I need a rail pass or anything of the sort, but will most likely buy point-to-point tickets mostly, unless convinced I need something otherwise. I don't fully know what I want to do with housing, as I'm going solo and try to do a backpacker type of vacation, where I don't want to spend on housing accommodations if I can help it, I'm very open and flexible with anything such as hostels or sleeping in the street if I need to do it.
Any help or recommendations in any area in terms of pricing or how to actually do all of this or anything that I should see in these cities would be greatly appreciated as everyone here seems to be helpful and knowledgeable, thanks!