Hi Kim,
The most important thing is a good fit. It can be adjusted somewhat by changing things like the stem or handlebars but if the size and geometry of the frame are wrong for you then no adjustment will be able to make you comfortable, and being uncomfortable (or in pain) tends to make cycling far less fun! For example, my first road bike was a regular (men's) Trek and reach to the handlebars was just too long for me, which caused shoulder and neck problems. Switching to a WSD (women-specific) Trek bike made a world of difference because the top tube is angled differently, which makes the reach shorter. Also it has a more compact handlebar with is more comfortable for my hands. But of course everyone is different -- for some women a men's frame is fine.
It helps immensely if the people working at the bike shop understand good bike fit. While you are shopping, ask them about how they help make sure the bike you buy fits you correctly. Before I bought both of my road bikes, the people at my LBS put the bike on an indoor trainer and watched me pedal it to see if the basic fit was good and if I needed to change any components, e.g., get a different size stem. Also during test rides, pay attention to your arms and shoulders -- are you very stretched out trying to reach the handlebars, are you shoulders hunched up, can you ride comfortably in the drops (holding the curved part of the handlebars below the shifters).
Have fun and good luck!
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles