Check your regs yourself, but the Columbia in the Portland area is open for retention Thu-Sat for sturgeon. Willamette will not open for retention until Nov. 1 and then only on Thu-Sat. Both rivers open for catch and release otherwise.
Best bait for me is squid, but also herring, shrimp, smelt and pickled baits. I use a slider for weight above a swivel and then a leader of heavy dacron (50-80lb. depending on what you are after) with a 5/0 to 9/0 barbless octopus hook. Smaller end of those ranges work for most except the oversize. If you use anything large (herring, squid, smelt, etc.) half-hitch up the bait after hooking through head to hold in place. Smaller baits use stretchy thread to hold on if necessary. Use scent if you want.
If you want to fish the Columbia put in at Cathedral Park on the Willamette or other ramp and head out into Columbia and look for other boats and anchor up in the general area. Popular areas on the Willamette are just downriver from Cathedral Park (the Toyota Hole about 100' deep) or in the Sellwood bridge area. Lots of other areas but that is a start.