How do I get rid of the old paint so I can repaint them?

On my most recent rental, the existing paint was OK (not bad enough to repaint, but not perfect), so I was planning on repainting the entire property a few years down the road anyway.  

Of course, the repainting will be done by my contractor. 

No repainting or replacing of siding to worry about.

Both jobs were about $25K including windows and repainting the entire house.  

Repainted every wall and the ceiling too.

I notice apartments tend to go with wood siding products and just keep repainting every so often....though generally not often enough.  

I could save $3000 just by not re-painting the entire house inside and out (the house was painted 3 years ago and is "okay"; I would just only paint the bad areas) and leaving the crappy kitchen countertop and kitchen cabinets.  

If you're keeping the siding you could just repaint a new color like light blue or dark grayish blue for window trim just do simple frames and for light blue paint window frames trim and outer doors and dark blue including garage door make sure to match garage door with front door it looks sloppy when they don't match. if you're changing the front you could try flat stone in charcoal grey and match the siding on the sides do the house with same paint color.

Why not just repaint with high quality floor paint or refinish and polly.