Yeah, some tips:
Do not go for less than 8GB of memory.
Try to stick to a quad core or better CPU.
Do not get a video card with less than 192bit path. The higher this path, the better the card performance. Think of it as a multi lane highway between two cities. The more lanes you have, the more traffic can pass. So the larger that bitpath, the faster the card can process data between the motherboard and the video card. (well memory/cpu bus, but you get the idea)
Get a good quality power supply. Do not skimp on this. 50 bucks or more should be spent on one. 12V single rail. Many higher end game systems won't have one less than a 100 bucks.
Motherboard. Again, you want a decent quality board. Asus, Gigabyte, Asrock, Biostar, and a few others make good boards, providing you stick to their higher dollar models. Many have a list of features, and there are sites all over that make many recommendations. Most of my builds use the first 3 of those. I have never preferred Biostar, but I know they can make good stuff. Same with MSI. Avoid Elite and some of those cheaper builders.
Memory. Often you can get a 2 piece or 4 piece kit. Kingston, Corsair, AData, are decent to name a few. First two can be kinda high sometimes. Be sure to check for what the board can use before choosing.
Hard drives vs SSD. Comes down to price and performance. For a good gaming rig I try to stick to WD Black series. These are 5 year warranty drives, and offer a nice punch for a mechanical without totally busting the budget. If you want pure speed, get an SSD drive, with AT LEAST around 300-400 read/write speeds and no smaller than 100GB. Faster is better. You can use a drive like this for the OS and some programs, and keep data on a second mechanical drive. Makes the computer insanely fast, but doesn't fill it full of things too quick.
Anyway, good luck!