Tren, for an avanced user, is very good for strength. If you are new to gear, just test alone will give you massive strength gains, but if you have been around the block and want to add a strength drug to your cycle, tren will help. Not only is it good for physical strength, but it is also good for mental aggression in the gym. 100mg EOD of tren ace is a standard dose but some people are more sensitive to it than others. I find that at first, my central nervous response is high to the more androgenic drugs. Starting out at a lower dose is a good idea, to see how it effects you. 50mg EOD for a few wks will make a difference in strength and then from there, you can evaluate how things are going and decide if you want to increase or not.
Remember that although strength is good from tren, it can also cause a loss in cardio. Guys tend to get more winded on tren, so if your goal is to do a power lifting meet, then sure, tren will help, but if you are looking to punch harder in MMA, tren might not be your best bet.
Other good drugs to look into for strength would be halo or anadrol. Both are oral and both are toxic. Tren can be pretty toxic too, so be careful with these compounds and respect them. Anavar is good for strength and is what I would suggest for guys that want strength for their sport but also need to keep their stamnia.
With any of these, test is the base of any cycle!