Age is relative like experience. There are experienced people and not very experienced people in all age groups. Attitude about sex is more key than whichever age a person is.

Not opposed. I have had a few, but I really prefer a lover who is casual and comfortable with themself, their body and their sexuality. Virgins rarely know what they want or feel, more experienced people know what they like and crave. I like assertive but not aggressive. I enjoy naive but not so timid as many virgins tend to be.
There are some techniques. Re-reading previous works can help. Reading some poorly written stories can motivate your "I can write better" urges. Reading something outside your usual genre stimulates the "I would have done it differently.". Find a new muse that inspires and surprise yourself with an unlikely imagined hookup.