When we bought our house, we had terrible problems with the cable. Time warner came out and said sorry you have too many splitters (3) and too much cable buried in the ceiling in the basement. I got them to leave a roll of cable (a lot of companies will do this for you if it means they don't have to waste time running cable) and started ripping things apart (ceiling was stapled in place tile type so that wasn't much of a loss anyway). I went through and put home runs (straight from every connection point back to service drop) whoever there was going to be a possible spot for a tv now and in the future. Bought a good 8 way splitter and a good 2 way. Split my service drop with the two, ran the line for the modem into the two way and another line to the 8 way for the tv cables. I bought my own Thomas and Betts snap and seal connectors, an inexpensive connection tool and the proper stripper. With wall plates (kills me when they come and drill holes in your floor) and the keystones for the cable I was out less than 100$. With a couple weekends invested, all my problems were solved. I did have the tech out to replace the line from the connection on the house to the first splitter (which he couldn't be bothered to run it the way I wanted which would have required an extra 1.5 seconds of his time and approximately 2 more feet of the cable so I ended up redoing myself anyway) because the line coming in looked to be less than rg59 thickness and appeared to be from the early 80's at best.
After he checked the signal and said we still needed an amp to run everything, but couldn't hook it up because there wasn't an outlet nearby, he left one behind and said "you can make cables, I'm sure you can figure this out when there's power there", took off with out bedroom cable inoperative because he said the signal wasn't strong enough. Didn't make sense to me as everything was working great before he came, even with the ancient incoming cable. I went down stairs to double check everything and found he had replaced both my splitters with their own, a two way and a 5 way as that's all I had hooked up to mine at the time (I had the 75 ohm caps on the unused ones). I asked my wife who had been there before I got home and she said he replaced my "cheap" ones with theirs because theirs were better. I went back, found mine he had placed on a shelf, re-installed them, and voila! Perfect reception to the formerly non functioning tv (which happens to be the longest run by several feet). A few weeks later, I ran power to the cabinet I installed the cabling in, hooked up the amp, and no difference. Didn't need it after all I guess.
So, long story short, replace all your questionable cable, split it as few times as possible (try and have your modem on its "own" line to minimize db loss as much as possible). And take your time, it's not as hard as it looks. The same tech that came questioned my cable install because "nobody does it right", spent a half hour before he even started replacing the incoming line, going around and taking apart all the wall plates and other connections to check my terminations. After he was done with that he gave my wife a card and told her if I ever needed a job to call his supervisor. I did it with cheaper tools, nothing fancy, just paid attention to what I was doing. Don't rush it and all will be fine.
Try and use what your cable company uses, it'll help minimize any questions that arise. And don't use cheap cable if you have to buy your own. Most quad shield isn't needed, the newer "duo shield" is just as good if not better, and a bit easier to work with as quad has the extra layer and is slightly stiffer. You also don't need to buy top of the line for most uses, no need to buy 3ghz certified super ultra high end of you just have a few cable boxes and 50gb internet.
