First of all, you don't have to lower your triceps parallel to the floor when you do a pushup, just go down until it feels like you're doing something right, keep doing pushups from time to time and workout your triceps any other way you can and you'll be able to do a hundred pushups the 'right' way no fucking sweat, including all the variants that await you down the road.
Second of all, you work your compound movements first, then you do isolations. Next, you try and work your largest muscles first then your smaller muscles. And machines come after free-weight and body-weight exercises - these are the three rules you should know before you ever start. You don't have to follow them every time, as you won't always work out the whole body in one day - you might have arms or legs day. Stretch from top to bottom or bottom to top - this isn't all mandatory but it is basic principle.
Don't go lifting heavy shit you can't lift enough times to actually break a sweat or you're just going to tire out your muscles before you've even started, don't feel self-conscious about lifting something lighter than what those fucking Chad's are lifting. Buy yourself some dumbbells, you can find a 40lb set at Walmart for no more than $20 - do full body workouts, do some shadow-boxing or in-place cardio and exercises like squats and pushups, planks and crunches, you name it. Try and get out more, just walking to the store and back, or to wherever and back, walk around stores more often looking for the best prices, carry groceries instead of using a shopping cart. Every little bit helps. Proper form and a healthy understanding of basic nutrition and body chemistry is a must. Lift correctly, move correctly, run correctly, or risk it all before you even start. You're going to start seeing people wearing braces and knee wraps all over the damn place - this is a sign of improper form more so than over-working - consider compression sleeves if you think form is a hard thing to grasp
I'll post what I've got (but you should already be scanning the stickies and QTDDTOT's for more info).