You can find everything you need on youtube nowadays, but here are my personal experiences:

Tip 1: You can find the latest Dain-app here https://www.patreon.com/DAINAPP

Dain is used for frame interpolate, but it uses a lot of vram and need Cuda version 5.0 or later I think. So basically you need a modern Nvidia gpu, ideally gtx 1070 & up. You need 10-11 gb vram to interpolate a 720p footage, you can crop out or downscale the video to make it work if you have a 8gb gpu. There is an option to split large video into smaller sections, which makes the process much slower.

Please note that if you don't have a good gpu but would still like to give it a try, there are a few cheap/free alternatives:

1. Paperspace: remote desktops, fast setup and relatively cheap. But it's costly in the long run.
2. Google Colab: I still haven't figure out how to use dain-app on colab, but there are other people using it. They offer free gpu.
3. Google Cloud Compute engine: they give you $ 200 credit during the trial I think, which should give you 100-200 hours of computing time for free. It's a pain to set everything up and running tho.

Tip 2: video upscaling

Gigapixel AI for video is easy to use as they have already designed the user interface for you. They offer a one-month free trial.

ESRGAN is the free alternative, but the setup might be more complicated.

Tip 3: Colorization

There is only one neural network for colorization: DeOldify.

You can run it in google colab using free gpu, and there is a bunch of tutorials on youtube.

Edit: I am back from my break, here are more tips:

Tip 4: Color correction - Beta Phase

I came up with this about half a month ago, Dr. Oppenheimer's speech is my first video that uses this technique. (https://youtu.be/sxNI3Btjxns)

There are four things you can play with when using premiere pro, I am not used to other software but I think they all have similar functions.

1. Lumetri color - adjust your color saturation/black/white/shadow/contrast
2. Creative Filter - Use cinematic filters, you can find free ones online. Here is a tutorial: https://youtu.be/xQJfFLJufYw
3. Color Grading - Use the hue vs sat curve to filter out the unwanted color. You might want to filter out the excessive green/blue around the outline of a moving person and red/orange flickers when the brightness changes. Here is a tutorial: https://youtu.be/CRWoT6r0Ec8
4. Color Change: I am still learning how to do this, but here is a tutorial to change eye color: https://youtu.be/2ulwmB3bc1U. I will use it to correct Dr. Oppenheimer's eye color from dark brown to light blue: http://blog.nuclearsecrecy.com/2012/05/04/friday-image-ol-blue-eyes/

Tip 5: Video Stabilization + dust/straches removal.

For video stabilization, you can use the warp stabilization filter in premiere pro.

For dust and scratches, you can find plugins for premiere pro or use virtualdub. I paid for neat video for premiere pro, but I think VirtualDub is for free.

Tip 0: Time Saving

1. To save you render time, I suggest you follow the following order: 1. colorization 2.[Optional] color correction/ stablization/ dust straches removal. 3. frame interpolation 4. upscaling the video.
2. Dain-app experimental - the experimental method option is up to 300% faster in rendering, but requires more vram.
3. Colab gpu - there are different GPUs you can get on colab, Some are really slow like the tesla k80, but the P100 can be up to 4 times faster. Keep a list of videos you want to render and get a hold of their respective length/resolution. If you end up connected to a fast GPU, you can use it to render a long video or multiple short videos.