I think your real problem may be anxiety or obsessive compulsive disorder and you have focused on HIV. But here are the tips you asked for.You may want to talk to a psychologist about this obsession if it persists.
Here's How To Use A Condom:
1. Most condoms are made of latex so check the expiry date before use.
2. If your condom is in a box it most likely comes with a leaflet - worth reading.
3. Open the condom wrapper but don't tear it with teeth or use scissors. You do not want to perforate the condom- that gives no protection at all!
4. Hold the teat end of the condom between your forefinger and thumb.
5. If needed, pull back the foreskin to expose the head of the penis.
6. roll the condom the length of the erect penis.
7. NEVER use oil-based lubricants with a condom as it will disintegrate in moments. Always use water or silicone based lubricants.
8. After sex withdraw the penis while it is still erect making sure you hold the condom on while withdrawing.
9. Never re-use a condom; dispose of it after use.
10. Men with a latex allergy could consider using a natural membrane but these are less effective in terms of preventing pregnancy.
As for blood.
As long as there is no transmission of blood to blood or blood to body fluid,then you are safe. In other words,never exchange needles or have sex without condoms as minute traces of blood can be found in body fluids.