I have a dynamic IP address and I don't want to change it every time I connect to the Internet. I want to get a static IP address; what can I do?
To get a dynamic IP address on your LAN, simply assign your address statically within the LAN subnet, but outside the IP address ranges configured by the DHCP server - ie if your LAN range is 192.168.0.0 netmask 255.255.255.0, with a gateway of 192.168.0.1 and your DHCP server is set to allocate IP addresses from the range 192.168.0.100 to 192.168.0.200, configure your computer to use 192.168.0.101, netmask 255.255.255.0, gateway 192.168.0.1 - For nameservers either use 18.104.22.168 (Googles nameservers) or 192.168.0.1 (most home routers act as nameservers as well) (Alternatively If you have a fancy DHCP server you can dynamically assign a static address)
Getting an externally accessible IP address is somewhat harder, and, I suspect, what you are after.
The "correct" way to do this is to ask your ISP for one. If they are unwilling to oblige, you could find a "Low End Box" / Virtual Server, configure OpenVPN on that along with NAT, connect your network to it and then use the Low End Box IP address. Alternatively, you might be able to find a VPN provider who will do this for you (but I could not find one with a quick Google search)
An alternative would be to shift to IPV6. If your provider won't give you a static IPv6 allocation, you can use an IPV6 tunneling service to get one - the major limitation here being that the side you are connecting from needs to talk IPV6 as well.
A Dynamic DNS provider is, as others have suggested, a convenient work-around to many static IP address problems (but certainly not all, for example working with places with firewall rules you need to get through)
If you're talking about your WAN IP, you need to contact your ISP. Otherwise, you could use a dynamic DNS service like No-IP, if the problem is it being consistent.
If you're just talking about your LAN IP, some routers allow you to lease based on MAC address, or you could just go to Network Settings, right click your adapter, Properties, IPv4, Properties and change it to an IP address within your LAN range.