How to dig safely next to basement wall
Exactly how deep a trench are you planning, and how wide? I realize this is your own house, and from the sounds of it you are financially pressed, but in the commercial world, any trench 3 or more feet deep is OSHA regulated. People can and do routinely die in trench collapses due to improper use of trench supports, failure to use trench supports, or greater soil pressure than anticipated. The safest way to do trench work is to slope the sides of the trench back at a safe angle, which is typically flatter than 45 degrees. Of course, this means more digging, and sometimes it is not possible to slope the trench back, hence the use of trench support technology such as sheeting, tiebacks, trench boxes etc.
The use of trench support equipment is normally way beyond DIY stuff, certainly designing such a system over the internet is irresponsible and potentially fatal to you. The need for support depends entirely on the geometry of the trench, the soil conditions, and the water table. If your trench would trigger OSHA controls, regardless of whether you are actually subject to such controls due to this being your house, you need to understand the safety procedures at a minimum. Unfortunately they are complex and lengthy.
conclusion: If your project is dangerous enough to warrant trench support, this is probably not a good DIY project.