Mandovoodoo nailed it, but I’ll add my 2c.

I started out with a Cannondale hybrid: shocks on seat post and forks, but lighter than on a MTB. This served me very well as a getting back into the saddle motivator. As others have said, ride often and add to your distance. Your fitness will improve quicker than you might think if you keep a regular schedule. As my fitness improved I made changes to the bike; first off I tossed the gel saddle and bought a true road saddle, next I dropped tire size from 32 to 25. These two things made a big difference, but not one that I would have noticed/appreciated when I first returned to riding. I added. Time pedals and bar end grips for more hand positions as my rides grew from 14 mi to into the 20s and time in saddle went from 35 min to 75 min. At the end of 4 months I was ready to move to a true road bike, and with my albeit limited experience I was better prepared to make a more informed purchase. I bit the bullet and purchased a TREK PILOT 5.0. Three seasons later, and riding over 4000 miles a season I LOVE my PILOT. BTW - I have changed out the seat post on the Cannondale to a nonsuspention post and have added fenders, this is now my rain/winter ride.

Soo… the advice to not spend too much on bike no1 is one I agree with, mine was $900 plus mods as described. Don’t go too cheep as you want it to be reliable and to function well i.e. shift/break ($800-$1100). Initially, tires should be 25-28s. These will ride smother and flat less than traditional roadie 23s. (I now ride 23 on front and a 25 rear) Ride often but do not push yourself too hard as some injuries take a long time to recover from and this can be very discouraging, but do add miles as you can tolerate. Most noobies spin too slow – i.e. mash. Learn to spin at 90 rpm, this saves knees and builds lungs… Start every ride with tires properly inflated. Bike fit is VERY important. Purchase bike clothing, it makes riding much more enjoyable. You’ll need to experiment with sizes as they vary from mfg to mfg.- NO COTTON. You’ll need to try on pants so a LBS is the place to get these. EBay is a great place to grab other cloths until you get picky about fit and fabric etc. Wear bright colors to be seen. Learn how to change a tire and carry both a spare tube and pump. Drink before you are thirsty. Carry a cell phone and $5, just in case. Wear glasses, a yellow jacket or fly in the eye at 30mph can ruin a day. Aim for smiles / mile rather than MPH, if it isn’t fun you’re not going to get bit by the bug! Oh, and if you live in a snow belt, as I do,get a good trainer or develop a winter cardio program so that you do not have to start ea spring from scratch and 20 lbs heavier.