What do you need for mining?

Out of personal experience, don't invest into cloud mining contracts. Chances are you'll never gain a dime out of it and even if, then only after years of "mining". Cryptocurrencies fluctuate alot and if they crash down after you've invested into a cloud mining contract then you're screwed just like me. Tried it when BTC was at its peak last year and what happened? It went all the way down right afterwards.

As for home mining, it kind of depends which crypto you want to mine. BTC? Then you'd need some nice ASIC miner. ETH? Grab as many GPUs as possible. There's motherboards that support 6 to 10/12 GPUs at the same time.
Keep in mind that your setup should be as cost effective as possible. Usually people go for the RX 470/480/570/580 or the GTX 1050/1060. I personally would advice against using more expensive cards like the GTX 1070/1080 or the RX Vega cards, but that's up to you.

A typical GPU mining rig would be something like this:
- Intel Celeron (single-core cpu)
- 2-4 GB of RAM
- 64-128 GB SSD
- 4-10 GPUs
- H110 Pro BTC+ Motherboard or something similar. This one has 7 PCI-E slots
- PCI-E riser cables
- Mounting frame

You may need to tune and tweak your GPU cards to get the most possible power out of it (with BIOS mods).

Use the nicehash.com calculator to estimate profits